JPH09200952A - Controller of ac-dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To operate, keeping active power and DC voltage in conformity with a set value, and minimizing the ripple of the active power and DC voltage of a sound converter even if the converter stops due to fault, in a DC transmission system constituted of plural converters. SOLUTION: This is a DC transmission system composed of a plurality of AC-DC converters 3 connected in series circuit. In the case that the difference between the set values of the active power that a converter 3 supplies and the detected value or the detected value of the active power deviates the preset range, DC voltage set value is corrected by adding the value proportionate to the magnitude of deviation, and the control is made so that the corrected DC voltage set value and the DC voltage detection value may be equal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an AC / DC converter, which is applied to a DC power transmission system including an asynchronous interconnection system and a frequency conversion system in a power system.

[0002]

2. Description of the Related Art FIG. 65 shows a configuration example of a DC power transmission system applied to a power system and using a self-excited AC / DC converter. One AC busbar 1 to converter transformer 2
The self-excited converter 3 is connected via
A capacitor 4 is installed on the DC terminal side of, and a self-excited converter 3'having the same configuration as the self-excited converter 3 is connected to the DC circuit beyond that. The self-excited converter 3'is connected to another AC busbar 1'through a converter transformer 2 '. Since the control device and the detection device have the same configuration for both the converter 3 and the converter 3 ', only one self-excited converter 3 is shown in FIG.

In this DC power transmission system, one of the self-excited converter 3 and the self-excited converter 3'is operated for forward conversion and the other is operated for reverse conversion, thereby accommodating active power between the AC buses.

Specifically, on the side of the self-excited converter 3, the DC voltage detector 5 detects the DC voltage Ed, and the active power detector 6 detects the active power Pa. , Active power set value Pref is matched, and each difference is input to the DC voltage / active power control circuit 7. Further, the reactive power detector 8 detects the reactive power Qa, matches it with the reactive power set value Qref, and inputs the difference to the reactive power control circuit 9.

In the DC voltage / active power control circuit 7 and the reactive power control circuit 9, the output signal is controlled so that the respective detected values and set values become equal. The output value of the DC voltage / active power control circuit 7 and the output value of the reactive power control circuit 9 are given to the AC control circuit 10 as a set value Idref of the active power component and a set value Iqref of the reactive power component of the AC current, respectively. .

On the other hand, the AC output current of the converter is detected by the three-phase / two-phase conversion circuit 11, and the detected value is converted into the active power component Id and the reactive power component Iq and given to the AC current control circuit 10.

In the AC current control circuit 10, the active power component detection value Id and the reactive power component detection value Iq of the AC current are set values of the active power component of the AC current which is the output of the DC voltage / active power control circuit 7, respectively. Idref, the set value Iqref of the reactive power component of the alternating current output from the reactive power control circuit 9
The phase angle φ of the PWM control signal and the control rate Cm that are equal to are calculated and given to the PWM control circuit 12.

In the PWM control circuit 12, the phase detection circuit 1
3 and the voltage phase θ of the AC bus 1 and the phase angle φ of the PWM control signal supplied from the AC current control circuit 10.
And the control rate Cm, the carrier wave signal and the three-phase sine wave PW
The M control signal is generated, and the on-pulse and off-pulse generation timings are determined by matching the two signals. The pulse generation circuit 14, which has received the timing signal thus determined, generates on-pulses and off-pulses for the self-excited converter 3 and gives them to the converter 3. The converter 3 is operated by turning on / off each semiconductor element forming the converter by this pulse.

By using such a control circuit,
In the DC power transmission system, the electric power according to the active power setting value Pref is exchanged from the forward converter side to the inverse converter side, and each converter outputs the reactive power according to the reactive power setting value Qref to operate. Be seen. Here, the reactive power has its own set value in each converter and is independently controlled, while the active power and the DC voltage are controlled in cooperation with both converters. Specifically, by controlling active power with one converter and controlling the DC voltage to be constant with the other converter,
While maintaining a constant DC voltage, the active power according to the set value is exchanged from the forward converter side to the inverse converter side.

A control system shown in FIG. 66 has been proposed as a DC voltage / active power control circuit 7 for realizing cooperative control of active power and DC voltage. The control method shown in FIG.
It is applied to a two-terminal DC power transmission system including one forward converter and one inverse converter. For details, see the literature (Journal of the Institute of Electrical Engineers of Japan, Volume 112, No. 1, pages 19 to 26).
It is stated in.

In the DC voltage / effective voltage control circuit 7 to which the control system shown in FIG. 66 is applied, the set value Edp of the DC voltage is compared with the detected value Ed, and the difference is given to the DC voltage control circuit 15 to be effective. The set value Pref of electric power is compared with the detected value Pa of active power, the difference is given to the active power control circuit 16, and the output is controlled so that the detected value becomes equal to the set value. Further, the output value of the active power control circuit 16 is used as the lower limit value for the output of the DC voltage control circuit 15.

Here, the DC voltage set value E is set on the forward converter side.
The DC voltage rated value is given as dp, and the inverse converter side is given a value about 10% smaller than the rated value in order to avoid interference with the forward converter side. This causes the output of the DC voltage control circuit 15 to reach the lower limit value on the inverse converter side, and the output of the active power control circuit 16 given as the lower limit value becomes the final output Idref. On the forward converter side, the output of the DC voltage control circuit 15 becomes the final output Idref as it is. As a result, the DC voltage can be controlled according to the rated value on the forward converter side, and the necessary interchange power can be controlled on the inverse converter side.

Further, in the above-mentioned document, the cooperative control of active power and DC voltage is applied to a so-called multi-terminal DC power transmission system in which three or more converters are connected by a DC circuit to exchange active power with each other. A control scheme is proposed in FIG. 67 for implementation.

In the DC voltage / effective voltage control circuit 7 to which the control system shown in FIG. 67 is applied, two different kinds of DC voltage set values EdpH and EdpL are set, and the DC voltage control circuit 151 of the first stage is set to DC. The voltage detection value Ed is controlled to be equal to the set value EdpH, and the DC voltage control circuit 152 in the second stage controls the DC voltage detection value Ed to be equal to the set value EdpL. The active power control circuit 16 performs control so that the set value Pref of the active power becomes equal to the detection value Pa, and outputs the output value of the direct current voltage control circuit 151 of the first stage.
Used as the upper limit value for the output of. Further, the output of the first-stage DC voltage control circuit 151 is given to the input terminal b of the switch circuit 17, and the other input terminal a is given a fixed value Idmin, such as −120%.

The switch circuit 17 selects and outputs the value given to either the input terminal a or the input terminal b, and outputs the output value from the second-stage DC voltage control circuit 15
Used as the lower limit value for the 2 output. Finally, the output of the DC voltage control circuit 152 of the second stage is output as the set value Idref of the active power component of the AC output current and given to the AC current control circuit 10.

In one of the plurality of converters constituting the DC power transmission system, the switch circuit 17 selects the input terminal a, and the DC voltage setting value EdpL is 100% of the rated voltage.
give. In other converters, the input terminal b is selected by the switch circuit 17, and as the DC voltage set value, for example, in one converter, EdpH, which is 110% of the rated voltage.
%, EdpL is 90% of the rated voltage, EdpH of the other converter is 120% of the rated voltage, and EdpL is 80% of the rated voltage. EdpH is larger than the rated voltage, and EdpL is smaller than the rated voltage. Values that are different by about 10% between the converters.

As a result, the converter whose input terminal a is selected by the switch circuit 17 is subjected to DC voltage control by the operation of the DC voltage control circuit 152 of the second stage so as to have a rated voltage, and the other converters. Then, since the output of the active power control circuit 16 becomes the final output Idref, active power control is performed so as to perform power interchange according to the given active power set value Pref.

When the converter performing the DC voltage control stops or the output limiter is applied, among the remaining converters, the converter to which the DC voltage set value close to the rated voltage is given is newly added. DC voltage control operation will be performed.

A system shown in FIG. 68 has been proposed as a control system for realizing cooperative control of active power and DC voltage. The control method shown in the figure is applied to a multi-terminal DC power transmission system, and the details are described in the literature (IEEJ Power Technology Research Group PE-95-120).

In the DC voltage / active power control circuit 7 to which the control system shown in FIG. 68 is applied, the difference between the active power set value Pref and the active power detection value Pa is amplified by the amplifier 19 having a constant amplification factor r. , And the difference ΔEd between the DC voltage setting value Edp and the DC voltage detection value Ed is added to obtain the corrected DC voltage difference ΔEd ′. The DC voltage control circuit 15 performs control so that the corrected DC voltage difference ΔEd ′ becomes zero.
The output of the DC voltage control circuit 15 is output as the set value Idref of the active power component of the AC output current, and given to the AC current control circuit 10.

When the control device having this configuration is used, FIG.
The relationship between the DC voltage and the active power is obtained as shown in. That is, when the detected value Pa of the active power is equal to the set value Pref, the DC voltage is controlled to be the value as the set value Edp, and when there is a difference between the detected value of the active power and the set value, it is proportional to the difference. As a result, the DC voltage changes, and the characteristic becomes a downward slope as shown in FIG.

When this control circuit is used in each converter constituting the DC power transmission system, when the active power set values of the entire DC power transmission system are balanced, that is, the sum of the active power set values given to the converters is summed up. When is zero, the converters transfer active power according to the set value, whereby the DC voltage is controlled to the value according to the initially applied DC voltage set value. When an unbalance occurs in the active power setting value given to each converter due to an accident or the like, that is, when the sum of the active power setting values of each converter becomes non-zero, the unbalanced component is converted into the amplification factor r by each converter. Compensate accordingly. As a result, a difference occurs between the active power setting value Pref and the detection value Pa, the DC voltage setting value Edp is corrected, and the DC voltage is initially given E.
It is controlled by a value different from dp.

[0023]

However, in the control method shown in FIGS. 66 and 67, the converter is controlled so that the DC voltage becomes the rated value in the normal state. However, the converter that controls the DC voltage is used. Is stopped or the output limit value is exceeded, the converter to which the DC voltage setting value different from the rated value is given performs DC voltage control operation. Therefore, there is a problem that the operation is continued in a state where the DC voltage is decreased or increased by about 10% from the rated value, the stress of the device is increased due to the overvoltage or the overcurrent, or the control characteristics are deteriorated. It was

Further, in the case of the multi-terminal DC power transmission system, even if some converters are stopped due to an accident or the like, the power can be exchanged between the remaining healthy converters to continue the operation. In that case, when the control device to which the control method shown in FIG. 67 is applied is used, the power change amount of the stopped converter is compensated only by the converter performing the DC voltage control.
There is a problem that the active power of the converter that controls the DC voltage is likely to fluctuate and the output limit value is easily exceeded.

Further, in the control system shown in FIG. 68, the unbalanced portion of the active power is shared by the converters to compensate, and it is difficult to obtain the active power operating value as set.
Also, since the set value of the DC voltage is corrected by the difference between the set value of the active power and the detected value, the DC voltage can be changed with the set value different from the given value even if the imbalance of the active power is not so large. There was a problem that it was difficult to obtain a direct current voltage that was controlled and was rated.

The present invention has been made in view of the above circumstances, and a DC transmission system including a plurality of converters operates while maintaining active power and DC voltage as set values, and further, Even if some of the multiple converters stop due to an AC system accident or breakdown, or the operating value of the active power changes, the active power and DC voltage fluctuations of a healthy converter should be minimized. An object of the present invention is to provide a control device for an AC / DC converter that can continue operation.

[0027]

In order to achieve the above object, the present invention takes the following measures.

The present invention corresponding to claim 1 is a controller of an AC / DC converter in a DC power transmission system, wherein a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit. If the difference between the set value of active power and the detected value or the detected value of active power deviates from the preset range, correct the DC voltage set value by adding a value proportional to the size of the deviation, A circuit is provided to control the corrected DC voltage set value and the DC voltage detection value to be equal.

According to the controller of the AC / DC converter of the present invention,
If the difference between the active power setting value and the active power detection value, or the active power detection value deviates from the preset range, the DC voltage setting value is added by adding a value proportional to the deviation. Will be corrected. The active power setting value is generated such that the corrected DC voltage setting value and the DC voltage detection value are equal. Therefore, if this controller is used to control the AC / DC converter that constitutes the DC power transmission system,
When the operating value of the active power is within the specified range, the DC voltage is controlled according to the set value, and when the operating value of the active power deviates from the specified range, the operating value of the active power is prevented from deviating further. In addition, the DC voltage control can be performed so as to suppress the fluctuation of the DC voltage to be small.

According to a second aspect of the present invention, in a controller of an AC / DC converter in a DC power transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, setting of DC voltage is performed. The difference between the detected value and the detected value is controlled so that the value obtained by multiplying the difference by the proportional constant is zero, and the difference between the set value of active power of the converter and the detected value or the detected active power is When a deviation from a preset range is provided, a circuit is provided to control the deviation and the multiplication value to be equal.

According to the controller of the AC / DC converter of the present invention,
A value obtained by multiplying the difference between the detected value of the DC voltage and the set value by a proportional constant is calculated, and control is performed so that the multiplied value becomes zero. On the other hand, if the value of the difference between the set value of active power and the detected value or the detected value of active power deviates from the preset range, the deviated magnitude is calculated, and the value of the deviated magnitude and the DC voltage detection value The difference between the set values is controlled to be equal to the value obtained by multiplying the proportional constant. Therefore, if this control device is used to control the AC / DC converter that constitutes the DC power transmission system, the DC voltage is controlled so that it is within the set range of the active power operating value, and the active power operating value is controlled. When the value of ∘ deviates from a certain range, the control value is controlled so as to prevent the operating value of the active power from deviating further and suppress the fluctuation of the DC voltage to be small.

According to a third aspect of the present invention, in a controller of an AC / DC converter in a DC power transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, a DC voltage set value is set. If the value of the difference between the DC voltage detection value and the DC voltage deviates from the preset range, the converter corrects the set value of the active power accommodating by adding a value proportional to the deviated magnitude. The corrected active power setting value and the active power detection value are controlled to be equal.

According to the controller of the AC / DC converter of the present invention,
The difference between the DC voltage set value and the DC voltage detected value is calculated, and when the difference deviates from the preset range, a value proportional to the deviated magnitude is added to correct the active power set value. The corrected active power setting value and the active power detection value are controlled to be equal. Therefore, if this control device is used to control the AC / DC converter that constitutes the DC transmission system, the active power is controlled according to the set value and the operation value of the DC voltage is constant within the range where the operation value of the DC voltage is constant. When the value deviates from the range of 1, the control can be performed so as to prevent the operating value of the DC voltage from deviating further and suppress the fluctuation of the active power to be small.

According to a fourth aspect of the present invention, in a controller for an AC / DC converter in a DC power transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, the converter interchange is provided. The difference between the set value of active power and the detected value is calculated, and the difference is multiplied by a proportional constant so that the value is controlled to be zero, and the difference between the set value of the DC voltage and the detected value is within a preset range. In the case of deviation, a circuit is provided so as to control the magnitude of deviation and the multiplication value to be equal.

According to the controller of the AC / DC converter of the present invention,
A value obtained by multiplying the difference between the detected value of active power and the set value by a proportional constant is obtained, and if the difference between the set value of the DC voltage and the detected value deviates from the preset range, the deviated magnitude is calculated. It Then, control is performed so that the value of the deviated magnitude, the difference between the active power detection value and the set value are multiplied by a proportional constant. Therefore, if this controller is used to control the AC / DC converter that constitutes the DC power transmission system, the active power is controlled so that it is within the set range within the operating range of the DC voltage. When the value deviates from a certain range, it is possible to perform control so as to prevent the operating value of the DC voltage from deviating further and suppress the fluctuation of the active power to be small.

According to a fifth aspect of the present invention, in a controller for an AC / DC converter in a DC power transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, the converter interchange is provided. A correction for correcting both of the two different DC voltage setting values by adding a value proportional to the difference between the active power setting value and the detected value to each of the two different DC voltage setting values. Means, a first-stage DC voltage control circuit for performing control so that the larger one of the two types of DC voltage set values corrected by the correction means and the detected DC voltage are equal, and the correction means is used for correction. The DC voltage control circuit in the second stage that controls the smaller of the two types of DC voltage setting values to be equal to the detected value of DC voltage, and the setting value and the detected value of the active power that the converter accommodates. Become equal And a valid power control circuit for cormorants control, using the output of the active power control circuit as the upper limit value for the output value of the DC voltage control circuit of the first stage,
The output of the first-stage DC voltage control circuit is used as a lower limit value to the output value of the second-stage DC voltage control circuit,
The output of the DC voltage control circuit in the second stage is used as a final control output value for the DC voltage and active power.

According to the controller of the AC / DC converter of the present invention,
A value proportional to the difference between the set value of active power and the detected value is added to the DC voltage setting values of two different values, respectively, and both of the two different DC voltage setting values are corrected.
The DC voltage control circuit of the first stage performs control so that the larger one of the corrected two types of DC voltage setting values becomes equal to the detected value of the DC voltage. The DC voltage control circuit in the second stage controls so that the smaller value becomes equal to the detected value of DC voltage, and further the active power control circuit controls so that the set value and detected value of active power become equal. .
At this time, the output value of the active power control circuit is used as an upper limit value for the output value of the first-stage DC voltage control circuit, and the output of the first-stage DC voltage control circuit is the second-stage DC voltage control circuit. Used as the lower limit for the output of the circuit,
Further, the output of the DC voltage control circuit in the second stage is used as the final control output for the DC voltage and active power. Therefore, when the operating value of the DC voltage is within a certain range, the active power is controlled so as to be the set value, and when the operating value of the DC voltage deviates from the certain range, the operating value of the DC voltage is further increased. The control can be performed so as to prevent a large deviation from occurring and suppress the fluctuation of the active power to be small.

The present invention corresponding to claim 6 corrects the DC voltage set value by adding a value proportional to the difference between the set value of the active power and the detected value, and the corrected DC voltage set value is in a fixed range. Is controlled so as not to deviate from the above, and control is performed so that the limited DC voltage setting value and the DC voltage detection value become equal. Therefore, if this control device is used to control the AC / DC converter that constitutes the DC power transmission system, while the operating value of the DC voltage is restricted so as not to deviate from a certain range, it will change when the active power detection value changes from the set value. By controlling by changing the DC voltage set value in proportion to the ratio, it is possible to control the DC voltage so that it does not largely deviate from the initially set value while suppressing fluctuations in active power.

In the invention corresponding to claim 7, three kinds of DC voltage set values having different values are provided, and the difference between the DC voltage set value and the DC voltage detected value which is an intermediate value among the three kinds of DC voltage set values. The active power control circuit corrects the active power set value by adding a value proportional to the active power set value, and performs control so that the corrected active power set value becomes equal to the active power detected value. The first-stage DC voltage control circuit for controlling the DC voltage setting value of the largest DC voltage setting value and the DC voltage detection value to be equal, and the DC value of the smallest value of the three types of DC voltage setting values. A second-stage DC voltage control circuit for performing control so that the voltage setting value and the DC voltage detection value are equal to each other is provided, and the output of the active power control circuit is an upper limit value with respect to the output value of the first-stage DC voltage control circuit. Used as The output of the first-stage DC voltage control circuit is used as a lower limit value with respect to the output value of the second-stage DC voltage control circuit, and the output of the second-stage DC voltage control circuit is used as a DC voltage. A control circuit is provided for use as the final control output for active power.

According to the present invention, when the operating value of the DC voltage is limited so as not to deviate from a certain range, when the detected value of the DC voltage changes from the set value of the DC voltage, the active power set value is set in proportion to the change rate. By changing and controlling, the fluctuation of the DC voltage can be suppressed to be small, and the control value can be controlled so that the operating value of the active power does not largely deviate from the initially set value.

In the invention corresponding to claim 8, three kinds of DC voltage setting values having different values are provided, and an intermediate value of the three kinds of DC voltage setting values is set as an active power setting value. The correction is performed by adding a value proportional to the difference between the detected values. The first-stage DC voltage control circuit that controls so that the corrected DC voltage set value and the DC voltage detected value are equal, the DC voltage set value and the DC voltage detected value that are the largest of the three types of DC voltage set values. Control to be equal 2
A DC voltage control circuit at the third stage and a DC voltage control circuit at the third stage for controlling the DC voltage setting value of the smallest value among the three types of DC voltage setting values to be equal to the DC voltage detection value are provided. The output of the first-stage DC voltage control circuit is used as an upper limit value for the output value of the second-stage DC voltage control circuit, and the output of the second-stage DC voltage control circuit is used as the third-stage DC voltage. It is used as a lower limit value for the output value of the control circuit, and the output of the third-stage DC voltage control circuit is used as the final control output for the DC voltage and active power.

According to the controller of the AC / DC converter of the present invention,
While limiting the operating value of the DC voltage so that it does not deviate from a certain range, when the detected value of active power changes from the set value, the DC voltage set value is changed and controlled in proportion to the rate of change. It is possible to control so that the operating value of the DC voltage does not largely deviate from the initially set value while suppressing the fluctuation of

In the invention corresponding to claim 9, when the value of the difference between the set value and the detected value of the active power or the detected value of the active power deviates from the preset range, it is proportional to the deviated magnitude. A circuit that corrects the DC voltage setting value by adding values, limits the corrected DC voltage setting value so that it does not deviate from a certain range, and controls so that the limited DC voltage setting value and the DC voltage detection value become equal. Shall be provided.

According to the controller of the AC / DC converter of the present invention,
When the operating value of active power is within the set range, control is performed so that the DC voltage is as set, and if the operating value of active power deviates from the set range, the DC voltage remains within a certain range. It is possible to adjust the DC voltage while limiting it so as not to exceed the limit, and perform control so as to prevent the operating value of the active power from deviating further from the set range.

In the invention corresponding to claim 10, three different kinds of DC voltage setting values are provided, and the difference between the DC voltage setting value and the DC voltage detection value which is an intermediate value among the three kinds of DC voltage setting values. Is outside the preset range,
The set value of active power is corrected by adding a value proportional to the deviated magnitude. An active power control circuit that controls so that the corrected active power set value and the active power detected value are equal to each other, the DC voltage set value having the largest value among the three types of DC voltage set values is equal to the detected DC voltage. DC voltage control circuit of the first stage for controlling so that the DC voltage setting value of the smallest value among the three types of DC voltage setting values and the DC voltage of the second stage for controlling the DC voltage detection value become equal. A control circuit is provided, and the output of the active power control circuit is used as an upper limit value for the output value of the first-stage DC voltage control circuit, and the output of the first-stage DC voltage control circuit is used as the second-stage DC voltage. A circuit is provided which is used as a lower limit value for the output value of the voltage control circuit and which controls the output of the second-stage DC voltage control circuit as the final control output for the DC voltage and active power.

According to the controller of the AC / DC converter of the present invention,
When the operating value of the DC voltage is within a certain range, control is performed so that the active power detection value is equal to the active power setting value.If the operating value of the DC voltage exceeds the certain range, the ratio is exceeded. By controlling the active power value by changing it proportionally, the fluctuation of the DC voltage is controlled to be small, and when the operating value of the DC voltage fluctuates further, the DC voltage is controlled to be constant. As a result, it is possible to prevent the DC voltage from changing more greatly.

The invention corresponding to claim 11 is a multiplication obtained by multiplying a difference between a DC voltage set value of an intermediate value and a DC voltage detected value among three different kinds of DC voltage set values by a proportional constant. The value is controlled so that the value becomes zero, and when the value of the difference between the set value of active power and the detected value or the detected value of active power deviates from the set range, the value of the deviated magnitude and the DC voltage detection value And an active power control circuit for controlling the difference between the set values to be equal to a value obtained by multiplying the set value by a proportional constant, and the DC voltage set value having the largest value among the three types of DC voltage set values becomes equal to the detected DC voltage. DC voltage control circuit of the first stage for performing the above control, and DC voltage control of the second stage for performing the control so that the DC voltage set value of the smallest value among the three types of DC voltage set values becomes equal to the detected value of the DC voltage. Circuit, and the active power control circuit Is used as an upper limit value for the output value of the first-stage DC voltage control circuit, and the output of the first-stage DC voltage control circuit is a lower-limit value for the output value of the second-stage DC voltage control circuit. The output of the DC voltage control circuit in the second stage is controlled so as to be used as a final control output for the DC voltage and active power.

According to the controller of the AC / DC converter of the present invention,
Within the range where the operating value of active power is set, the DC voltage detection value is controlled so that it becomes equal to the intermediate value among the three DC voltage setting values, and the range where the operating value of active power is set In the case of deviation from the above, the DC voltage can be adjusted while limiting the DC voltage so as not to exceed a certain range, and the operating value of the active power can be prevented from deviating from the set range.

In the invention corresponding to claim 12, in the control device of the AC / DC converter in the DC transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by the DC circuit, the converters are interchangeable. If the difference between the set value of active power and the detected value or the detected value of active power deviates from the preset range, a value proportional to the size of the deviation is added to add DC voltage of three different values. Correction means for correcting an intermediate value among the set values, and a first-stage DC voltage control circuit for controlling the DC voltage set value corrected by the correction means to be equal to the DC voltage detection value, Of the three types of DC voltage setting values, the DC voltage control circuit of the second stage which controls so that the DC voltage setting value of the largest value and the DC voltage detection value are equal, and the three types of DC voltage setting values U And a DC voltage control circuit of a third stage for performing control so that the DC voltage set value of the smallest value and the DC voltage detection value become equal to each other, the output of the DC voltage control circuit of the first stage is output from the second stage. It is used as an upper limit value for the output value of the DC voltage control circuit, the output of the second-stage DC voltage control circuit is used as a lower limit value for the output value of the third-stage DC voltage control circuit, and the third stage is used. The output of the DC voltage control circuit is used as the final control output value for the DC voltage and active power.

According to the controller of the AC / DC converter of the present invention,
Within the range where the operating value of active power is set, control is performed so that the detected value of DC voltage becomes equal to the intermediate value among the three types of DC voltage settings, and the operating value of active power deviates from the set range. In this case, it is possible to prevent the operating value of active power from deviating from the set range by adjusting the DC voltage while limiting the DC voltage so as not to exceed a certain range.

According to a thirteenth aspect of the present invention, a value obtained by multiplying the difference between the set value of active power and the detected value by a respective proportional constant is used as a DC voltage set value, an upper limit value for the DC voltage set value, and a DC value. Corrected by adding each to the lower limit value for the voltage set value, and limiting the corrected DC voltage set value so as not to deviate from the range of the corrected upper limit value and the corrected lower limit value, and the limited DC voltage set value. And the DC voltage detection value are controlled to be equal.

According to the controller of the AC / DC converter of the present invention,
When the active power detection value changes from the set value, the DC voltage value is controlled by changing it from the initially set value according to the magnitude of the change, and the rate of change of the DC voltage due to this change in active power is controlled. It is possible to perform control so that different ratios are obtained when the detected value of active power is close to the set value and when it is far from the set value.

According to a fourteenth aspect of the present invention, in a controller for an AC / DC converter in a DC power transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, three types of values are provided. The DC voltage setting values of the three types described above are added to different DC voltage setting values by adding respective multiplication values obtained by multiplying the difference between the setting value of the active power of the converter and the detected value by each individual proportionality coefficient. And a first-stage DC for performing control so that the DC voltage detection value becomes equal to the value obtained by correcting the DC voltage setting value of the intermediate value among the three types of DC voltage setting values by the correction means. The voltage control circuit and the second-stage DC voltage for performing control so that the DC voltage detection value becomes equal to the value obtained by correcting the largest DC voltage setting value among the three types of DC voltage setting values by the correction means. Control circuit and a third-stage DC voltage control circuit for performing control so that the value obtained by correcting the smallest DC voltage setting value among the three types of DC voltage setting values by the correction means becomes equal to the detected DC voltage value. And 1
The output of the DC voltage control circuit of the second stage is used as an upper limit value for the output value of the DC voltage control circuit of the second stage, and
The output of the DC voltage control circuit in the third stage is used as a lower limit value with respect to the output value of the DC voltage control circuit in the third stage.
The output of the DC voltage control circuit at the stage is used as the final control output value for the DC voltage and active power.

According to the controller of the AC / DC converter of the present invention,
When the active power detection value changes from the active power setting value, the DC voltage value is controlled by changing it from the initial setting value according to the magnitude of the change, and the rate of change in the DC voltage due to this change in active power is Control can be performed so that different ratios are obtained when the operating value of the DC voltage is close to the set value and when it is far from the set value.

According to a fifteenth aspect of the present invention, the converter is flexible in the controller of the AC / DC converter in the DC transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit. A value that is proportional to the difference between the set value of active power and the detected value and the magnitude of the difference between the set value of the active power and the detected value that deviates from the preset range are added, and the added value is further set to the DC voltage set value. The DC voltage setting value is corrected by adding to, and the corrected DC voltage setting value and the DC voltage detection value are controlled to be equal.

According to the controller of the AC / DC converter of the present invention,
When the detected value of active power changes from the set value, the DC voltage value is controlled by changing it from the initial set value according to the magnitude of the change. It is possible to perform control so that different ratios are obtained depending on whether the detected value of electric power is close to the set value or far from the set value.

According to a sixteenth aspect of the present invention, in a control device for an AC / DC converter in a DC power transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, a DC voltage set value and A value proportional to the difference between the detected values of the DC voltage and the magnitude of the difference between the set value of the DC voltage and the detected value of the DC voltage deviating from the preset range are added, and the added value is further added to the set value of the active power. Thus, the set value of active power is corrected, and the corrected active power set value and the detected active power value are controlled to be equal.

According to the controller of the AC / DC converter of the present invention,
When the detected value of the DC voltage changes from the set value, the value of the active power is changed from the set value according to the magnitude of the change, and the control is performed. It is possible to perform control so that the detected value of 1 is close to the set value and that the detected value is significantly different from the set value so as to have different ratios.

According to a seventeenth aspect of the present invention, in a controller of an AC / DC converter in a DC power transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, the detected value of active power is detected. And a value proportional to the difference between the set value and the magnitude of the difference between the DC voltage set value of the intermediate value and the detected value of the DC voltage among the three different values of the DC voltage set value deviating from the preset range. DC voltage control circuit for controlling the DC voltage control circuit so that the DC voltage setting value and the DC voltage detection value are the same among the three types of DC voltage settings. A third DC voltage control circuit, and a third-stage DC voltage control circuit for performing control so that the DC voltage setting value of the smallest value among the three types of DC voltage settings becomes equal to the DC voltage detection value. , The first stage The output of the flow voltage control circuit is used as an upper limit value for the output value of the second-stage DC voltage control circuit, and the output of the second-stage DC voltage control circuit is used as the output value of the third-stage DC voltage control circuit. And the output of the third-stage DC voltage control circuit is used as the final control output value for the DC voltage and active power.

According to the controller of the AC / DC converter of the present invention,
When the operating value of the DC voltage is within the set range, control is performed so that the active power is the value that is set, and if the operating value of the DC voltage deviates from the set range, the value of the DC voltage is changed. If the operating value of the DC voltage fluctuates even further, the DC voltage is controlled to a constant value by adjusting the active power setting value accordingly. Controls can be provided to prevent the voltage from fluctuating any further.

According to the eighteenth aspect of the present invention, the DC voltage set value is corrected by adding a value proportional to the power of the difference between the set value of the active power and the detected value that the converter accommodates, and the corrected DC voltage is corrected. Control is performed so that the voltage setting value and the DC voltage detection value are equal.

According to the controller of the AC / DC converter of the present invention,
When the detected value of active power changes from the set value of active power, the DC voltage value is controlled by changing it from the set value according to the magnitude of the change. It is possible to perform control so that different ratios are obtained depending on whether the detected value of electric power is close to the set value or far from the set value.

According to the nineteenth aspect of the present invention, the active power set value interchanged with the converter is corrected by adding a value proportional to the power of the difference between the set value of the DC voltage and the detected value, and the corrected active power is corrected. The set value and the active power detection value are controlled to be equal.

When the detected DC voltage value changes from the DC voltage set value, the controller of the AC / DC converter of the present invention changes the value of the active power from the set value according to the magnitude of the change and controls the value. It is possible to perform control so that the rate of change in active power due to the change in DC voltage becomes different depending on whether the detected value of the DC voltage is close to the set value or greatly separated from the set value.

[0065]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

(First Embodiment) FIG. 1 shows a first embodiment in which the control device for an AC / DC converter of the present invention is applied to a multi-terminal DC power transmission system. Although only the control device of the AC / DC converter 3 is shown in the figure, the control devices of the other AC / DC converters 3 ', 3 "also have the same configuration. The multi-terminal DC power transmission system according to this embodiment is shown in FIG.
It has the same system configuration as the DC power transmission system shown in. Therefore, the same parts as those of the system shown in FIG.

In the control device of the AC / DC converter shown in the same figure, the DC voltage detector 5 detects the DC voltage Ed, the active power detector 6 detects the active power Pa, and the detected values are used as the DC voltage / active power. Input to the control circuit 70.

The DC voltage / active power control circuit 70 inputs the difference between the set value Pref of the active power and the detected value Pa to the amplifier 19 having a constant amplification factor r via the dead zone circuit 18, and the output of the amplifier 19 Is added to the DC voltage setting value Edp to obtain a corrected DC voltage setting value Edp '. The difference between the corrected DC voltage set value Edp 'and the DC voltage detection value Ed is calculated by using the DC voltage control circuit 1 including, for example, a proportional integration circuit.
Enter in 5. The DC voltage control circuit 15 controls the output so that the detected value Ed of the DC voltage becomes equal to the corrected set value Edp '. This output is used as the set value Idref of the active power component of the alternating current.

The dead zone circuit 18 outputs zero when the difference between the input value, that is, the set value Pref of the active power and the detected value Pa is within the set dead range, and when the input value exceeds the dead range. It is a circuit that outputs an exceeding size. Further, the DC voltage control circuit 15 is provided with upper and lower limit values determined by the rated capacity of the converter, etc.
dref is restricted to not exceed this range.

The reactive power detector 8 detects the reactive power Qa, matches it with the reactive power set value Qref, inputs the deviation to the reactive power control circuit 9, and detects the detected value and the set value Q.
The output signal is controlled so that ref becomes equal, and the set value Iqref of the reactive power component is given to the AC control circuit 10. Further, the AC output current of the converter is detected by the three-phase / two-phase conversion circuit 11, and the detected value is converted into the active power component Id and the reactive power component Iq and given to the AC current control circuit 10.

In the alternating current control circuit 10, the PWM control signal of the active power component detection value Id and the reactive power component detection value Iq are equal to the active power component set value Idref and the reactive power component set value Iqref, respectively. Phase angle φ and control rate C
m, and the PWM control circuit 12 calculates the phase detection circuit 13
PWM of the carrier wave signal and the three-phase sine wave from the voltage phase θ of the AC bus 1 given by the above, the phase angle φ and the control rate Cm of the PWM control signal given from the AC current control circuit 10.
A control signal is generated and the generation timing of the on-pulse and the off-pulse is determined by matching the two signals. The pulse generation circuit 14 that has received the timing signal determined in this way generates an ON pulse and an OFF pulse for the converter 3 and gives them to the converter 3.

The operation contents of the control device for the AC / DC converter configured as described above will be described in detail.

In the control device for the converter 3 having the configuration shown in FIG. 1, if the difference between the active power set value Pref and the detected value Pa is within the dead range of the dead zone circuit 18, the outputs of the dead zone circuit 18 and the amplifier 19 are output. Becomes zero, and the final DC voltage setting value E
dp 'becomes a value equal to the set value Edp before correction. Therefore, the DC voltage control circuit 15 performs control so that the DC voltage becomes equal to the initially set value Edp, and the converter performs DC voltage control based on the DC voltage set value Edp.

On the other hand, when the difference between the active power set value Pref and the detected value Pa becomes large and exceeds the dead range of the dead zone circuit 18, a value proportional to the exceeded value becomes the output of the amplifier 19 and the DC voltage setting is made. The value is added to the value Edp to obtain the final DC voltage set value Edp '. Therefore, the DC voltage is controlled to be a value different from the DC voltage set value Edp initially given according to the magnitude of the detected value of active power.

The characteristics of the active power and the DC voltage will be described with reference to FIG.

FIG. 2 comprises three converters, an AC / DC converter 3 (= converter A), an AC / DC converter 3 '(= converter B), and an AC / DC converter 3 "(= converter C). It is a characteristic view which shows the active power of each converter of a multi-terminal DC power transmission system, and the relationship of DC voltage.

Each of the three converters has the same circuit configuration as the DC voltage / active power control circuit 70 shown in FIG. 1, and the rated voltage 100% is commonly given as the DC voltage set value Edp. Be present. Points a, b and c in FIG. 2A and points a ′ and b ′ in FIG.
c'is the operating point of each converter.

Here, for example, if the dead range ΔPref of the dead zone circuit 18 is set to ± 50% for the converter A and 0% for the converters B and C, the converter A is given an effective power operating value and is effective. Within the range of ± 50% of the power setting value Pref A, the DC voltage is constant, and beyond that range, the DC voltage decreases as the active power increases and decreases to the right, and the DC voltage increases as the active power decreases to the left ascending characteristics. Becomes Since the converters B and C have no dead range, they always have a downward sloping characteristic. When the DC voltage is the set value, the active power is operated so that it is the set value. The power increases above the set value, and when the DC voltage increases, the active power operates so as to decrease below the set value.

As a result, if the active power operating point of the converter A is within the dead range, that is, between Pref A + ΔPref and Pref A−ΔPref, as shown by the point a in FIG. By performing constant DC voltage operation of A, the DC voltage is maintained at the value set as Edp. In converters B and C, since the DC voltage is the set value, the active power is also set at the points b and c. Be driven in. At this time, the sum of the active power operation values of the converters is zero, that is, a balanced state.

On the other hand, for example, when the polarity of the active power set value Pref B in the converter B is inverted and becomes a positive value from the operating state of FIG. 2 (a), as shown in FIG. 2 (b), The sum of the active power set values of the converter becomes a positive value and the unbalanced part is shown in Fig. 2.
Increased compared to (a). In order to maintain the balance of active power, the active power operating point of the converter A moves in the negative direction to point a ', which is smaller than the minimum value Pref A-ΔPref in the dead range. As a result, the converter A shifts from the operation in which the DC voltage is constant to the operation in a straight line rising to the left, and the DC voltage rises. Due to the increase in the DC voltage, the active power operating points of the converters B and C move in the negative direction from the set values, and the sum of the active powers of the converters including the converter A is zero. And equilibrium at points b ′ and c ′.

As a result of the above, the operating points of active power in converter B and converter C do not match the set values, but converter A
The active power operating point of is a value closer to the set value than when the converters B and C are operated at the values according to the set value. That is, when the unbalanced portion of the active power set value of the entire DC circuit is small, the converter A performs constant DC voltage control while absorbing the unbalanced portion of the active power, and the active power set value of the entire DC circuit is adjusted. When the unbalanced amount becomes large, the converters share and absorb the unbalanced component, thereby operating so as to prevent the active power operating value of the converter A from largely deviating from the set value. Further, in the converter A, the possibility that the output of the DC voltage control circuit 15 will reach the upper and lower limiters is reduced.

FIG. 3 shows the results of a simulation comparison of the operating characteristics when the control circuit of this embodiment is applied and when the conventional control circuit is applied.

FIG. 3A shows the case where the control circuit of this embodiment is applied, and FIG. 3B shows the case where the conventional control circuit shown in FIG. 67 is applied. It shows the deviation of the voltage, that is, the difference with respect to the set value Edp.
The active power setting value Pref is 60% for the converter A and 60% for the converter C.
Is -60%, and in converter B, 0% is changed to -60%. When this embodiment is applied, the dead range ΔPref of the converter A is set to ± 50%, and the converters B and C are
Has no dead range. Further, in the case of applying the conventional control circuit, the DC voltage setting value of the converter A is 100%, and the two kinds of DC voltage setting values of the converters B and C are the converter B
Is EdpL = 90%, EdpH = 110%, and the converter C is EdpL.
L = 80% and EdpH = 120%. The output limit value of each converter is ± 125% in both cases.

In the initial state, the sum of active power set values is zero, that is, they are balanced, and only the circuit loss appears as an unbalanced portion. Therefore, there is almost no difference between the operating points in both systems, and converters B and C Indicates that the converter A absorbs the circuit loss and operates at an active power slightly different from the set value. The DC voltage is the value as set.

When the active power set value of the converter B is changed to -60% from this state, the active power imbalance increases, and in the conventional system of FIG. 3B, the converter A has an output limiter of 125%. The operation, the converter B becomes the DC voltage control operation, and the converter C becomes the active power control operation. Therefore, the converter A has a large difference between the active power set value and the operating value, and the converter B performs the DC voltage control, so that the DC voltage is reduced by 10% from the rated value. On the other hand, as shown in FIG. 3 (a), when the control according to the present embodiment is applied, the active power operating value of the converter A deviates from the dead range, but the DC voltage of the converter A changes regardless of the output limiter. The decrease is significantly improved to 0.2%. The difference between the active power set value and the operating value of the converters B and C is almost the same as in the conventional method.

As described above, according to the present embodiment, the dead zone circuit 18 calculates the difference between the set value Pref of the active power and the detected value Pa.
Is input to the amplifier 19 via the, and the output of the amplifier 19 is added to the DC voltage set value Edp and corrected to correct the DC voltage set value Ed.
Since p'is obtained and the set value Idref of the active power component is obtained from the difference between the DC voltage set value Edp 'and the DC voltage detected value Ed, normally, the DC voltage is kept as the set value and each conversion is performed. The device can accommodate active power as set. Also, if the unbalanced portion of the active power set value of the entire DC transmission system becomes large due to the stop of the converter or the change of the active power constant value due to an accident, each converter shares the unbalanced portion of the active power. It is possible to prevent the operating value of the active power from deviating largely from the set value in the specific converter by absorbing. Furthermore, by preventing the difference between the set value of active power and the operating value from increasing in a specific converter, the converter is less likely to be in limiter operation, and the DC voltage changes significantly due to limiter operation. Can be prevented.

(Second Embodiment) FIG. 4 shows the internal structure of a DC voltage / active power control circuit in a control device for an AC / DC converter provided in a DC power transmission system according to a second embodiment. .

Since the DC power transmission system according to this embodiment has the same system configuration as that of the DC power transmission system shown in FIG. 1, the DC voltage / active power control circuit, which is a different part, will be described in detail. This embodiment differs from the first embodiment in that the difference ΔEd between the DC voltage set value Edp and the detected value Ed is corrected by adding the output of the amplifier 19.

That is, the DC voltage / active power control circuit 7
At 0, the difference ΔEd between the set value Edp of the DC voltage and the detected value Ed
Is calculated, while the difference between the set value Pref of the active power and the detected value Pa is calculated. The difference between the set value Pref and the detected value Pa is given to the amplifier 19 having a constant amplification factor r through the dead zone circuit 18, and the output of the amplifier 19 is the difference ΔE of the DC voltage.
A difference ΔEd ′ of the DC voltage corrected by adding to d is obtained.
The corrected DC voltage difference ΔEd ′ is applied to the DC voltage control circuit 15. The DC voltage control circuit 15 controls so that the difference ΔEd ′ of the corrected DC voltage becomes zero. The output of the DC voltage control circuit 15 is the active power component setting value Idr of the AC current.
Become ef. Dead band circuit 18 and DC voltage control circuit 15
Are set in the same manner as in the first embodiment.

In the converter control device configured as described above, if the difference between the active power set value Pref and the detection value Pa is a value within the dead range of the dead band circuit 18, the dead band circuit 18,
The output of the amplifier 19 becomes zero, and the final DC voltage difference ΔEd ′ becomes equal to the DC voltage difference ΔEd before correction. Therefore, the DC voltage control circuit 15 controls so that the DC voltage becomes equal to the set value Edp.

On the other hand, when the difference between the active power set value Pref and the detected value Pa is large and exceeds the dead zone of the dead zone circuit 18, a value proportional to the exceeded magnitude becomes the output of the amplifier 19 and the difference ΔDC of the DC voltage. To ΔEd ′, and the DC voltage control circuit 15 controls so that ΔEd ′ becomes zero. Therefore, the DC voltage is controlled to be a value different from the DC voltage set value Edp initially given according to the magnitude of the detected value of active power.

Therefore, when the same setting as that of the first embodiment is made to the control device of each exchanger constituting the multi-terminal DC power transmission system, the characteristics of active power and DC voltage are shown in FIG. Then, the relationship is the same as the characteristics of active power and DC voltage in the first embodiment described above.

(Third Embodiment) The third embodiment is an example in which a dead zone range for the active power detection value Pa is set in the dead zone circuit and the detection value Pa is input to the dead zone circuit.

Since the multi-terminal DC power transmission system according to the third embodiment has the same system configuration as the DC power transmission system shown in FIG. 1, the DC voltage / active power control circuit which is a different part will be described in detail. To do.

FIG. 5 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the third embodiment.

This DC voltage / active power control circuit 70 is
The active power detection value Pa is given to the amplifier 19 having a constant amplification factor r via the dead band circuit 18, and the output of the amplifier 19 is added to the DC voltage setting value Edp with a negative polarity to correct the corrected DC voltage setting value Edp. Get ′. The corrected DC voltage set value Edp 'and the DC voltage detection value Ed are compared and the deviation is input to the DC voltage control circuit 15. In the DC voltage control circuit 15, the detected DC voltage value Ed is the corrected DC voltage set value Ed.
Control the output to be equal to p '. The output of the DC voltage control circuit 15 is set to the set value Idref of the active power component of the AC current.
To the AC current control circuit 10.

The dead zone circuit 18 outputs zero if the input value, that is, the active power detection value Pa is within the set dead range, and outputs the exceeded value if the input value exceeds the dead range. Is set to. The DC voltage control circuit 15 is provided with upper and lower limit values determined by the rated capacity of the converter and the like, and the output Idref is limited so as not to exceed this range.

In the controller of the AC / DC converter configured as described above, if the active power detection value Pa is a value within the dead range of the dead zone circuit 18, the outputs of the dead zone circuit 18 and the amplifier 19 become zero, and the DC The final voltage setting value Edp 'is equal to the uncorrected setting value Edp. As a result, the DC voltage control circuit 15 controls the DC voltage so that the DC voltage has a value according to the initially set value Edp.

On the other hand, when the active power detection value Pa exceeds the dead zone of the dead zone circuit 18, a value proportional to the exceeded range becomes the output of the amplifier 19 and the DC voltage set value Edp.
To the final DC voltage set value Edp ′
Becomes Therefore, the DC voltage is controlled to be a value different from the normal DC voltage value Edp according to the magnitude of the active power detection value Pa.

FIG. 6 is a characteristic diagram showing the relationship between the active power and the DC voltage of each converter of the multi-terminal DC power transmission system consisting of three converters A, B, and C.

The converter A is provided with the DC voltage / active power control circuit 70 shown in FIG. 5, and the converters B and C are DC with a configuration in which the dead range is zero in the first embodiment shown in FIG. Voltage/
It is assumed that the active power control circuit 70 is provided. Also,
Each converter has a rated voltage of 100 as the DC voltage set value Edp.
% Is commonly given. Points a, b, c in FIG.
And points a ', b', c'are the operating points of each converter.
Pmax and Pmin are upper and lower limit values for the output of the converter A. Here, assuming that the dead range of the dead zone circuit 18 of the converter A is P1 to P2, the operating point of active power is P.
When the voltage is within the range of 1 to P2, the DC voltage is constant, and when the voltage is out of the range, the DC voltage decreases as the active power increases and decreases to the right, and the DC voltage increases as the active power decreases and the characteristics increase to the left. Become. Since the converters B and C have no dead range, they always have a downward sloping characteristic, and if the DC voltage is maintained at the set value, the active power is also operated at the set value and the DC voltage drops. Then, the active power increases above the set value, and when the DC voltage increases, the active power decreases below the set value. The active power operating point Pa of the converter A is Pa = − (Pb + Pc) with respect to the operating point Pb of the converter B and the operating point Pc of the converter C. As a result, the sum of the active power operation values of the entire DC power transmission system becomes zero, that is, the state is balanced.

If the active power operating point of the converter A determined in this way is within the dead range, that is, between P1 and P2, as shown by the point a in FIG. 6, the converter A performs constant DC voltage operation. As a result, the DC voltage is maintained at the value according to the set value Edp, and since the DC voltage is at the converter B and C as the set value, the active power is also operated at the points b and c according to the set values Pref B and Pref C. It

On the other hand, for example, the active power set values of the converters B and C are both large positive positive values PrefB 'and PrefC'.
In such a case, the active power of the converter A becomes a large negative value and falls below the lower limit value P1 of the dead range. In that case, the operating point becomes the point a'in FIG. 6, and the converter A shifts from the operation in which the DC voltage is constant to the operation in a straight line rising to the left, and the DC voltage rises. By increasing the DC voltage,
The active power operating points of the converters B and C move in the negative direction relative to the set values respectively, and equilibrium is achieved at the points b ′ and c ′ where the sum of the active powers of the converters including the converter A becomes zero. To do.

As a result, the operating points of the active powers of the converters B and C do not match the set values, but the active power operating points of the converter A are the values of the converters B and C according to the set values. The value is far from the lower limit value Pmin as compared with the case of driving.

That is, when the active power operating point of the converter A is sufficiently far from the upper and lower limit values of the output, the converter A maintains the DC voltage as the rated value by performing the DC voltage constant control. In addition, if the active powers of the converters B and C are exchanged according to the set values and the active power operating point of the converter A approaches the upper and lower limit values, the active power operating points of the other converters are adjusted. By doing so, the active power operating point of the converter A operates to prevent the limit operation from exceeding the upper and lower limit values.

As described above, according to the present embodiment, the active power detection value Pa is given to the amplifier 19 having a constant amplification factor r via the dead zone circuit 18, and the output of the amplifier 19 is set to a negative DC voltage set value Edp. The corrected DC voltage set value Edp 'is added by the sign, and the DC voltage set value Edp' and the DC voltage detected value Ed are controlled to be equal. Therefore, normally the DC voltage is set as the set value. While maintaining the same value, converters other than the specified converter that performs DC voltage control can exchange active power according to the set value, and the DC voltage can be changed by stopping the converter due to an accident or changing the active power set value. When the active power operating point of the converter to be controlled approaches the upper and lower limit values of the output, the active power of the other converters is adjusted to adjust the active power of the converter to perform DC voltage control. Operating point Prevented from becoming a limiter operation exceeds the low limit value, it is possible to prevent significant variations in the DC voltage due to the limiter operation.

(Fourth Embodiment) In the fourth embodiment, a dead zone range for the active power detection value Pa is set in the dead zone circuit, and the difference between the set value Edp and the detected value Ed is corrected by the output of the amplifier. This is an example of doing so.

Since the multi-terminal DC power transmission system according to the fourth embodiment has the same system configuration as the DC power transmission system shown in FIG. 1, the DC voltage / active power control circuit which is a different part will be described in detail. To do.

FIG. 7 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the fourth embodiment.

In this DC voltage / active power control circuit 70, the difference ΔEd between the DC voltage set value Edp and the detection value Ed is calculated, while the active power detection value Pa is passed through the dead zone circuit 18 to obtain a constant amplification factor r. The output of the amplifier 19 is added to the amplifier 19 having the same and is added to the DC voltage difference ΔEd with a negative sign to obtain a corrected DC voltage difference ΔEd ′. The corrected DC voltage difference ΔEd ′ is calculated by the DC voltage control circuit 15
To the corrected DC voltage difference Δ in the DC voltage control circuit 15.
The control is performed so that Ed 'becomes zero. DC voltage control circuit 1
The output of 5 becomes the active power component setting value Idref of the alternating current. The dead zone circuit 18 and the DC voltage control circuit 15 have a third
The same settings as those in the above embodiment are made. In the controller of the AC / DC converter configured as described above, when the active power detection value Pa is a value within the dead range of the dead zone circuit 18, the outputs of the dead zone circuit 18 and the amplifier 19 become zero, and the final DC The voltage difference ΔEd ′ has a value equal to the DC voltage difference ΔEd before correction. Therefore, the DC voltage control circuit 15 controls so that the DC voltage becomes equal to the set value Edp.

On the other hand, when the active power detection value Pa exceeds the insensitive range of the dead zone circuit 18, a value proportional to the exceeded value becomes the output of the amplifier 19 and the difference ΔE of the DC voltage.
It is added to d to become ΔEd ′, and the DC voltage control circuit 15
Then, control is performed so that the difference ΔEd ′ of the corrected DC voltage becomes zero. Therefore, the DC voltage is the DC voltage setting value Edp initially given according to the magnitude of the active power detection value.
The value is controlled to be different from.

Therefore, in the multi-terminal DC power transmission system including the three converters A, B, and C, the converter A is shown in FIG.
The DC voltage / active power control circuit 70 shown in FIG. 2 is provided, and the converters B and C are provided with the DC voltage / active power control circuit 70 having a configuration in which the dead range is zero in the first embodiment shown in FIG. By performing settings similar to those in the third embodiment, the characteristics of active power and DC voltage as shown in FIG. 6 can be realized.

As described above, according to the present embodiment, the difference ΔEd between the DC voltage setting value Edp and the detection value Ed is calculated, and the active power detection value Pa is passed through the dead zone circuit 18 and the amplifier having a constant amplification factor r. 19, the output of the amplifier 19 is added to the DC voltage difference ΔEd with a negative sign to obtain a corrected DC voltage difference ΔEd ′, and control is performed so that this difference ΔEd ′ becomes zero. The same effects as those of the third embodiment can be obtained.

(Fifth Embodiment) The fifth embodiment is an example in which the dead band range for the active power detection value Pa in the dead band circuit is set using the active power set value.

Since the multi-terminal DC power transmission system according to the fifth embodiment has the same system configuration as the DC power transmission system shown in FIG. 1, the DC voltage / active power control circuit which is a different part will be described in detail. To do.

FIG. 8 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the fifth embodiment.

In the DC voltage / active power control circuit 70, the set value Pref of active power and the dead range width ΔPref are given to the adders 211 and 212, and Pred + ΔPref is calculated by the adder 211 to obtain the output P2, Adder 21
2 is used to calculate Pref-ΔPref to obtain the output P1.
These P1 and P2 are given to the dead zone circuit 18 and used as the lower limit and upper limit of the dead range.

In the controller of the AC / DC converter configured as described above, the active power detection value Pa is equal to the active power set value Pref.
, The output of the dead zone circuit 18 and the amplifier 19 becomes zero, and the final DC voltage setting value Edp 'becomes equal to the DC voltage setting value Edp before correction. . Therefore, the DC voltage control circuit 15 controls so that the DC voltage becomes equal to the set value Edp.

On the other hand, when the active power detection value Pa exceeds the range of ± ΔPref with respect to the set value Pref, a value proportional to the exceeded value becomes the output of the amplifier 19 and is added to the DC voltage set value Edp. Becomes Edp ', and the DC voltage control circuit 15 sets the corrected set value Ed of the DC voltage detection value Ed.
Control is performed so that it becomes equal to p ′. Therefore, the DC voltage is controlled to be a value different from the DC voltage set value Edp initially given according to the magnitude of the detected value of active power.

As described above, according to the present embodiment, it is possible to obtain the same effect as that of the third embodiment, and the dead zone circuit 18 is made insensitive by the set value Pref of the active power and the dead range width ΔPref. The range can be set.

(Sixth Embodiment) In the sixth embodiment, a difference between the DC voltage set value and the detected value and an output of the insensitive circuit that receives the difference between the active power setting and the detected value are input. This is an example of controlling so that the two are equal.

Since the multi-terminal DC power transmission system according to the sixth embodiment has the same system configuration as the DC power transmission system shown in FIG. 1, the DC voltage / active power control circuit which is a different part will be described in detail. To do.

FIG. 9 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the sixth embodiment.

The DC voltage / active power control circuit 70 calculates the difference between the DC voltage detection value Ed and the DC voltage set value Edp, and also sets the active power set value Pref and the detected value Pa.
Is calculated. The difference between the DC voltage detection value Ed and the DC voltage setting value Edp is input to the amplifier 20 having a constant amplification factor K, the difference between the active power setting value Pref and the detection value Pa is input to the dead zone circuit 18, and the dead zone circuit 18 Output and amplifier 2
The outputs of 0 are matched and the deviation is input to the active power control circuit 16. The active power control circuit 16 controls so that the output of the dead zone circuit 18 and the output of the amplifier 20 become equal. The output is the set value Idr of the active power component of the alternating current.
Become ef.

The dead zone circuit 18 uses the active power set value Pref.
If the difference between the effective power detection value Pa and the active power detection value Pa is within the set dead range, zero is output, and if the input value exceeds the dead range, the exceeded value is output. Further, the active power control circuit 16 is provided with upper and lower limit values determined by the rated capacity of the converter, etc., and the output Idref is limited so as not to exceed this range.

In the control device for the AC / DC converter configured as described above, the dead zone circuit 18 is set if the difference between the active power set value Pref and the detected value Pa is within the dead range of the dead zone circuit 18.
Output is zero. Therefore, the active power control circuit 16 controls the DC voltage detection value Ed to be equal to the set value Edp.

On the other hand, when the difference between the active power set value Pref and the detected value Pa is large and exceeds the dead zone of the dead zone circuit 18, the active power control circuit 16 is controlled so that the excess and the output of the amplifier 20 become equal. Controls the active power. Therefore, the DC voltage is controlled to have a value different from the normal DC voltage value Edp according to the magnitude of the active power detection value.

Therefore, in the multi-terminal DC power transmission system consisting of three converters A, B and C, the converter A is shown in FIG.
The DC voltage / active power control circuit 70 shown in FIG. 2 is provided, and the converters B and C are provided with the DC voltage / active power control circuit 70 having a configuration in which the dead range is zero in the first embodiment shown in FIG. By performing the same setting as in the first embodiment, the characteristics of active power and DC voltage as shown in FIG. 2 can be realized.

According to this embodiment, the difference between the DC voltage detection value Ed and the DC voltage setting value Edp is input to the amplifier 20, and the difference between the active power setting value Pref and the detection value Pa is input to the dead zone circuit 18. Since the input is made and the output of the dead zone circuit 18 and the output of the amplifier 20 are matched, the output of the active power control circuit 16 is controlled so that they become equal.
When the difference between the set value Pref of the active power and the detected value Pa is within the dead range, the DC voltage can be controlled according to the set value, and when the unbalanced part of the set value of the active power of the entire DC transmission system becomes large. By sharing the active power imbalance by each converter and absorbing the active power imbalance, it is possible to prevent the operating value of the active power from largely deviating from the set value in the specific converter. Furthermore, by preventing the difference between the set value of active power and the operating value from increasing in a specific converter, the possibility of the converter operating in the limiter is reduced, and the large fluctuation of the DC voltage accompanying the limiter operation is reduced. Can be prevented. (Seventh Embodiment) A seventh embodiment is an example in which the difference between the DC voltage set value and the detected value is controlled to be equal to the output of the insensitive circuit to which the active power detected value is input. Is.

Since the multi-terminal DC power transmission system according to the seventh embodiment has the same system configuration as the DC power transmission system shown in FIG. 1, the DC voltage / active power control circuit which is a different part will be described in detail. To do.

FIG. 10 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the seventh embodiment.

In this DC voltage / active power control circuit 70, the difference between the set value Edp of the DC voltage and the detected value Ed is input to the amplifier 20 having a constant amplification factor K. On the other hand, the active power detection value Pa is input to the dead band circuit 18, the output of the dead band circuit 18 and the output of the amplifier 20 are matched, and the deviation is input to the active power control circuit 16. The active power control circuit 16 controls so that the output of the dead zone circuit 18 and the output of the amplifier 20 become equal, and the output is set as the set value Idref of the active power component of the alternating current. Dead zone circuit 18
Outputs 0 when the input value, that is, the active power detection value Pa is a value within the set dead range, and outputs a value exceeding the input value when the input value exceeds the dead range. The active power control circuit 16 is provided with upper and lower limit values determined by the power capacity rating of the converter, etc., and the output Idref is limited so as not to exceed this range.

In the control device for the AC / DC converter configured as described above, the output of the dead zone circuit 18 becomes zero if the active power detection value Pa is within the dead range of the dead zone circuit 18, so that the DC voltage setting is performed. The active power control circuit 16 controls the value Edp to be equal to the DC voltage detection value Ed.

On the other hand, when the active power detection value Pa exceeds the insensitive range of the dead zone circuit 18, the exceeded value and the output of the amplifier 20 are controlled to be equal. Therefore, the DC voltage is controlled to a value different from the normal DC voltage value Edp according to the magnitude of the detected value of active power, but it can be prevented that the operating point of active power deviates greatly from the set value and is applied to the limiter. .

Therefore, in the multi-terminal DC power transmission system including the three converters A, B, and C, the converters A to C are provided with the DC voltage / active power control circuit 70 shown in FIG.
By setting a predetermined dead zone for each converter, the characteristics of active power and DC voltage as shown in FIG. 6 can be realized.

According to such an embodiment, by configuring the DC power transmission system with the converter including the control circuit shown in FIG. 10, normally, the DC voltage control is performed while keeping the DC voltage as the set value. The converters other than the specified converters can exchange active power according to the set values, and by operating the converters that perform DC voltage control by stopping the converter due to an accident or changing the active power set value. When the point approaches the upper and lower limit values of the output, the active power operating points of the other converters are adjusted so that the active power operating values of the converters that perform DC voltage control exceed the upper and lower limit values. It is possible to prevent the limiter operation and prevent a large fluctuation of the DC voltage due to the limiter operation.

(Eighth Embodiment) The eighth embodiment is an example in which the dead zone of the dead zone circuit in the seventh embodiment can be automatically set based on the active power setting value.

Since the multi-terminal DC power transmission system according to the eighth embodiment has the same system configuration as the DC power transmission system shown in FIG. 1, the DC voltage / active power control circuit which is a different part will be described in detail. To do.

FIG. 11 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the eighth embodiment.

In this DC voltage / active power control circuit 70, the set value Pref of the active power and the dead range width ΔPref are given to the adders 211 and 212, and the adder 211 calculates Pref + ΔPref to obtain the output P2. The adder 212 calculates Pref-ΔPref to obtain an output P1, and these outputs P1 and P2 are given to the dead zone circuit 18 to be used as the lower limit value and the upper limit value of the dead range. Other configurations are the same as those of the control circuit shown in FIG.

In the controller of the AC / DC converter configured as described above, the active power detection value Pa is equal to the active power set value Pref.
On the other hand, if the value is within the range of ± ΔPref, the output of the dead zone circuit 18 becomes zero. Therefore, the active power control circuit 16 controls the DC voltage setting value Edp and the DC voltage detection value Ed to be equal.

On the other hand, the active power detection value Pa is the set value P
When the range of ± ΔP ref is exceeded with respect to ref, the exceeded level and the output of the amplifier 20 are controlled to be equal.
At this time, the DC voltage is controlled so as to have a value different from the normal DC voltage value Edp according to the magnitude of the detected value of active power, but the difference between the set value of active power and the operating value is large in a specific converter. Is prevented.

In a multi-terminal DC power transmission system consisting of three converters A, B, and C, a DC voltage / active power control circuit 70 shown in FIG. 11 is provided in converters A to C, and each converter has a predetermined dead zone. By setting, the characteristics of active power and DC voltage as shown in FIG. 6 can be realized.

According to such an embodiment, when the unbalanced portion of the active power set value of the entire DC transmission system becomes large due to the stop of the converter or the change of the active power set value due to an accident, each By the converter sharing and absorbing the active power imbalance, it is possible to prevent the operating value of the active power from largely deviating from the set value in the specific converter. Furthermore, by preventing the difference between the set value of active power and the operating value from increasing in a specific converter, the converter is less likely to be in limiter operation, and the DC voltage changes significantly due to limiter operation. Can be prevented.

(Ninth Embodiment) In the ninth embodiment, the difference between the DC voltage set value and the detected value is held at zero within a predetermined range, and if the difference exceeds the predetermined range, the excess amount is set. This is an example in which the set value of active power is corrected accordingly.

Since the multi-terminal DC power transmission system according to the ninth embodiment has the same system configuration as the DC power transmission system shown in FIG. 1, the DC voltage / active power control circuit which is a different part will be described in detail. To do.

FIG. 12 shows the internal structure of the DC voltage / active power control circuit in the control device for the AC / DC converter provided in the DC power transmission system according to the ninth embodiment.

In this DC voltage / active power control circuit 70, the difference between the DC voltage setting value Edp and the DC voltage detection value Ed is passed through the dead band circuit 22 to the amplifier 2 having a constant amplification factor K.
0 and input the output of the amplifier 20 to the active power setting value Pref
To obtain a corrected active power setting value Pref '. The corrected active power set value Pref 'is compared with the detected active power value Pa, the deviation is input to the active power control circuit 16, and the active power control circuit 16 corrects the active power set value Pref'. The control is performed so that it becomes equal to. The output is the set value Idr of the active power component of the alternating current.
Used as ef.

The dead zone circuit 22 outputs zero if the difference between the input value, that is, the DC voltage set value Edp and the DC voltage detection value Ed is within a preset dead range, and the input value exceeds the dead range. If it exceeds, the exceeded size is output. The active power control circuit 16 is provided with upper and lower limit values determined by the rated capacity of the converter, etc.
Is restricted not to exceed this range.

In the control device for the AC / DC converter configured as described above, if the difference between the set value Edp of the DC voltage and the detected value Ed is within the dead range of the dead zone circuit 22, the dead zone circuit 2
2. The output of amplifier 20 becomes zero, and the set value P of active power
ref 'becomes equal to the set value Pref before correction. Therefore, the active power control circuit 16 controls the active power so that the active power becomes a value according to the initially set value Pref.

On the other hand, when the difference between the DC voltage set value Edp and the detected value Ed becomes large and exceeds the dead range of the dead zone circuit 22, a value proportional to the size beyond the dead range is output from the amplifier 20. And is added to the active power setting value Pref to become the final active power setting value Pref '. Therefore, the active power is controlled to have a value different from the initially applied active power setting value Pref according to the magnitude of the fluctuation of the DC voltage.

FIG. 13 shows the effectiveness of each converter in the multi-terminal DC power transmission system in which the control circuit of FIG. 12 is applied to the two converters of the three converters A, B, and C that perform active power control. It is a characteristic view which shows the relationship between electric power and DC voltage. Here, converter A performs constant DC voltage control, and converters B and C
Is equipped with the control circuit shown in FIG.

A rated voltage of 100% is commonly given as a DC voltage set value Edp to each converter. FIG. 13 (a)
The points a, b, and c in Fig. 13 and the points a ', b', and c'in Fig. 13B are the operating points of each converter. Also, P
max and Pmin are upper and lower limit values for the output of the converter A, and the dead ranges of the dead band circuits 22 of the converters B and C are ± ΔEdB and ± ΔEdC, respectively.

By making the above settings, in the converters B and C, the operating value of the DC voltage is ± ΔEdB with respect to the given setting value Edp, and the active power is the setting value PrefB within the range of ± ΔEdC. Constantly controlled as PrefC, ± ΔEdB, ±
When the range of ΔEdC is exceeded, the direct current voltage decreases as the active power increases and decreases to the right, and as the active power decreases, the DC voltage increases to the left. Here, the dead range of the dead zone circuit 22, that is, ± 1% as the operating ranges ΔEdB and ΔEdC of the DC voltage for controlling the active power to be constant.
You can select a value of degree.

Compared with the conventional control circuit shown in FIG. 67, in the conventional control circuit, the set value of the DC voltage between the converters has a difference of ± 10 to 20%. In comparison,
The value of the insensitive range of the DC voltage of the control circuit according to the embodiment of the present invention is a small value. In the conventional control circuit, the DC power is switched from active power control to DC voltage control between the converters so that the converters in two or more locations operate simultaneously with constant DC voltage and unstable operation due to interference does not occur. While it is necessary to provide a difference of about 10% in the voltage level, in the case of the control circuit of the embodiment shown in FIG. 12, two or more converters are simultaneously moved down from the active power constant control to the right or Even if the operation is on the upward rising characteristic, there is a slope in the characteristic, so an intersection can be obtained and stable operation can be performed, so the range of the DC voltage for constant active power control can be reduced,
It is also possible to set this range to the same value for multiple converters.

Due to the above characteristics, the converters B and C are normally used.
Is controlled to output according to the given active power settings Pref B and Pref C, and the DC voltage is controlled by the converter A to a set value of 100%. Further, the active power operating value PA of the converter A is the active power set value Pref B of the converters B and C,
Equilibrate with respect to Pref C at the point PA =-(Pref B + Pref C). The value of this PA is as shown in FIG.
If the output limit values Pmin and Pmax of the converter A are within the range, the DC voltage is maintained at 100%.

On the other hand, as shown in FIG. 13B, PA
If the value of is out of the range of the output limit values Pmin and Pmax of the converter A, the converter A shifts from the constant DC voltage operation to the output limiter operation and the DC voltage changes. As a result, in the DC voltage / active power control circuit of the converter B or the converter C, the difference between the DC voltage setting value Edp and the detection value Ed becomes large and exceeds the dead range of the dead band circuit 22. In the case of the characteristics shown in FIG. 13, the width of the insensitive range of the converter C is set smaller than that of the converter B, so that the converter C negatively corrects the active power setting value Pref. As a result, the active power operating point of the converter C becomes a value in the negative direction from the set value PrefC ', and finally the operating points a', b ', and c'at which the sum of the active powers of the converters becomes zero. Equilibrate.

That is, when the active power operating point of the converter A is within the upper and lower limits of the output, the converter A maintains the DC voltage as the set value by performing the DC voltage constant control, and The rest of the converters to which the control circuit shown in FIG. 12 is applied exchange power according to the given active power setting value. If the active power operating point of converter A exceeds the upper and lower limit values of the output, or if converter A stops due to an accident, etc., adjust the active power setting values of other converters While minimizing the voltage change range,
The converter operates so as to be balanced at a point where the sum of active powers of the converters becomes zero.

FIG. 14 shows the results of a simulation comparison of the operating characteristics when the control circuit according to the present embodiment is applied and when the conventional control circuit is applied.

FIG. 14A shows the case where the control circuit of this embodiment shown in FIG. 12 is applied, and FIG. 14B shows the case where the conventional control circuit shown in FIG. 67 is applied. The simulation waveform of the deviation of the active power operating value of the converter and the DC voltage, that is, the difference with respect to the set value Edp is shown. The active power setting value Pref is -60% for the converter C,
In converter B, 0% is changed to -60%. In the case where the present invention is applied, the converter A performs constant DC voltage control, the converters B and C respectively use the control circuit according to the embodiment shown in FIG. 12, and the dead range ΔE of the dead zone circuit 22 is used.
dB, ∆EdC, ± 3% for both converters with respect to DC voltage setting
And In the case of applying the conventional control circuit, the DC voltage set value of the converter A is 100%, and the converter B and C are 2
The DC voltage setting value of the converter is EdpL = 90% for converter B,
EdpH = 110%, converter C has EdpL = 80%, EdpH
= 120%. The output limit value of each converter is ±
It is 125%. In this simulation, the active power operating value of the converter A is 70% in the initial state, which is within the output limit, so there is almost no difference in the operating points in both equations,
Converters B and C exchange active power according to the set value, and DC voltage is maintained according to the set value by converter A. When the active power set value of the converter B is changed to -60% from this state, the sum of the active power set values of the converter B and the converter C becomes + 120%, and the loss of the circuit is added to the sum. Is an output limiter operation of -125%. As a result, in the conventional method, the converter B performs the DC voltage control operation, so that the DC voltage decreases by 10%, whereas when the embodiment according to the present invention is applied, the conversion is performed when the DC voltage decreases by 3%. Since the converter B and the converter C respectively correct the active power setting values and adjust the values so that the sum of the active powers of the entire DC system becomes zero, the DC voltage fluctuation is about 3%, which is less than the conventional method. It is getting smaller. The active power operating point is almost the same as the conventional method.

From the above results, a DC power transmission system is constructed by combining a converter equipped with the control circuit of the embodiment shown in FIG. 12 and a converter for performing DC voltage control. The converters other than the converters that perform DC voltage control while maintaining the above conditions can exchange active power according to the set values, and the converters that perform DC voltage control can be changed by changing the active power set values. If the power operating point exceeds the upper and lower limit values of the output, or if the converter that performs DC voltage control stops due to an accident, the active power operating points of the other converters are changed according to the DC voltage change. By adjusting, the active power can be maintained at a value close to the set value and the operation can be continued while preventing a large fluctuation in the DC voltage.

In the above description, the three converters A,
Although the control circuit of FIG. 12 is applied to two converters of B and C, the same operation characteristics can be realized even when applied to a single converter.

(Tenth Embodiment) The tenth embodiment is different from the ninth embodiment in that the position where the detected value Pa is added to the set value of active power is the position before correction.

The multi-terminal DC power transmission system according to the tenth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 15 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the tenth embodiment.

In the DC voltage / active power control circuit 70, the difference ΔP between the set value Pref of the active power and the detected value Pa is calculated, while the difference between the set value Edp of the DC voltage and the detected value Ed is calculated in the dead zone circuit 22. It is input to the amplifier 20 having a constant amplification factor K via the output, and the output of the amplifier 20 is added to the difference ΔP between the set value and the detected value of the active power to obtain the corrected active power difference ΔP ′. This corrected active power difference ΔP ′ is
Input to the active power control circuit 16
The control is performed so that the active power difference ΔP ′ becomes zero, and the output is used as the set value Idref of the active power component of the alternating current.

The dead zone circuit 22 outputs zero if the input value is within the preset dead range, and outputs a value exceeding the dead value if the input value exceeds the dead range. The active power control circuit 16 is provided with upper and lower limit values determined by the rated capacity of the converter, etc., and the output Idref is limited so as not to exceed this range.

In the AC / DC converter controller configured as described above, if the difference between the set value Edp of the DC voltage and the detected value Ed is within the dead range of the dead zone circuit 22, the dead zone circuit 2
2. The output of the amplifier 20 becomes zero, and the active power setting value Pre
Since the difference ΔP between f and the detected value Pa is not corrected, the difference ΔP ′ of the active power input to the active power control circuit 16 is Δ.
It becomes equal to P. Therefore, the active power control circuit 1 is set so that the active power becomes a value according to the initially set value Pref.
The control is performed by 6.

On the other hand, when the DC voltage fluctuates and the difference between the DC voltage set value Edp and the detected value Ed increases and exceeds the dead range of the dead zone circuit 22, a value proportional to the exceeded value is output to the amplifier 20. Is added to the difference ΔP between the active power setting value Pref and the detection value Pa to form a final active power difference ΔP ′, which is provided to the active power control circuit 16.
Therefore, the active power is controlled to be a value different from the active power set value Pref initially given according to the magnitude of the fluctuation of the DC voltage, but the active power operating point of the specific converter is set to be different from the set value. Large deviations are prevented.

According to such an embodiment as well, as in the ninth embodiment, the active power operating point of the converter which controls the DC voltage by changing the active power set value or the like determines the upper and lower limit values of the output. If it exceeds or if the converter that controls the DC voltage stops due to an accident, etc., the active power of the other converters will be adjusted to the set value by adjusting the active power operating point according to the change of the DC voltage. While keeping close values,
The operation can be continued while preventing a large fluctuation in the DC voltage.

(Eleventh Embodiment) In the eleventh embodiment, the difference between the active power setting and the detected value and the output of the dead band circuit which receives the difference between the DC voltage set value and the detected value are input. This is an example of controlling to be equal.

The multi-terminal DC power transmission system according to the eleventh embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 16 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the eleventh embodiment.

This DC voltage / active power control circuit 70 is
The difference between the active power detection value Pa and the active power setting value Pref is input to the amplifier 19 having a constant amplification factor r, while the difference between the DC voltage setting value Edp and the DC voltage detection value Ed is input to the dead zone circuit 22. The output of the dead zone circuit 22 and the output of the amplifier 19 are matched, and the deviation is input to the DC voltage control circuit 15 configured by, for example, a proportional integration circuit. The DC voltage control circuit 15 controls so that the output of the dead band circuit 22 and the output of the amplifier 19 become equal. The output of the DC voltage control circuit 15 is used as the set value Idref of the active power component of the AC current.

The dead zone circuit 22 outputs zero if the difference between the input value, that is, the DC voltage set value Edp and the DC voltage detection value Ed is within a preset dead range, and when the input value exceeds the dead range. Will output the exceeded size.
The active power control circuit 15 is provided with upper and lower limit values determined by the power capacity rating of the converter, etc.
ef is limited so that it does not exceed this range.

In the present embodiment configured as described above, if the difference between the set value Edp of the DC voltage and the detected value Ed is within the dead range of the dead band circuit 22, the output of the dead band circuit 22 is zero. Therefore, the DC voltage control circuit 15 controls the active power setting value Pref and the active power detection value Pa to be equal.

On the other hand, when the difference between the set value Edp of the DC voltage and the detected value Ed exceeds the insensitive range of the dead zone circuit 22, the size beyond the insensitive range and the output of the amplifier 19 are controlled to be equal. . Therefore, the active power is the given active power set value P according to the magnitude of the DC voltage detection value.
It is controlled to have a value different from ref. The characteristics of the active power and the DC voltage are similar to those of the ninth embodiment described with reference to FIG.

Therefore, in the DC power transmission system configured as shown in FIG. 1, the DC voltage constant control is performed by one converter, and the remaining two converters are controlled by the converter.
When the control circuit shown in 6 is applied, if the active power operating point of the converter that performs constant DC voltage control is within the upper and lower limit values of the output, the converter performs constant DC voltage control Is maintained at the rated value, and the remaining converters perform power interchange according to the given active power set value.

On the other hand, if the active power operating point of the converter that performs constant DC voltage control exceeds the upper and lower limit values of the output, or if the converter that performs constant DC voltage control stops due to an accident, etc. By adjusting the active power set value of the converters, the converter operates so as to be balanced at the point where the sum of the active powers of the converters becomes zero while minimizing the variation width of the DC voltage.

According to such an embodiment, the difference between the active power detection value Pa and the active power set value Pref is input to the amplifier 19 having a constant amplification factor r, while the DC voltage set value Edp and the DC voltage are set. Since the difference in the detected value Ed is input to the dead zone circuit 22 and the output of the dead zone circuit 22 and the output of the amplifier 19 are matched to control the active power, normally, while keeping the DC voltage as the set value, For converters other than converters that perform DC voltage control, active power according to the set value can be accommodated, and the active power operating point of the converter that performs DC voltage control is output by changing the active power set value. If the upper and lower limit values of the above are exceeded, or if the converter that controls the DC voltage stops due to an accident, etc., the active power operating points of other converters can be adjusted according to the change of the DC voltage. , It can be continued while keeping the active power to a value close to the set value, to prevent substantial fluctuations in the DC voltage operation.

(Twelfth Embodiment) The twelfth embodiment of the present invention is a DC power transmission system including a control device for an AC / DC converter according to the present invention, and has the same system configuration as the DC power transmission system shown in FIG. Have.

FIG. 17 is a control block diagram showing the internal structure of the DC voltage / active power control circuit 70 provided in the control device for the AC / DC converter in this embodiment.

DC voltage / active power control circuit 7 shown in FIG.
At 0, the difference between the set value Pdref of active power and the detected value Pa is added to the adder 2 via the amplifier 19 having a constant amplification factor r.
31 and 232. Adders 231 and 232
Then, DC voltage setting values EdpH and Edp of different values
By adding L and the output of the amplifier 19, the corrected DC voltage set values EdpH 'and EdpL' are calculated. The corrected DC voltage set value EdpH 'is compared with the detected DC voltage value Ed, and the deviation is corrected to the first-stage DC voltage control circuit 1
51, and the direct-current voltage control circuit 151 of the first stage controls so that the detected direct-current voltage value Ed becomes equal to the corrected direct-current voltage set value EdpH '. Also, the corrected DC voltage set value E
The deviation is input to the second-stage DC voltage control circuit 152 by matching the dpL ′ and the DC voltage detection value Ed, and the DC voltage detected by the second-stage DC voltage control circuit 152 is corrected to the DC voltage. The control is performed so that it becomes equal to the set value EdpL '. Further, the active power control circuit 16 controls so that the detected value Pa of active power becomes equal to the set value Pref.

DC voltage control circuit 15 thus obtained
1, 152 and the output values of the active power control circuit 16, the output of the active power control circuit 16 is used as an upper limit value for the output of the first stage DC voltage control circuit 151, and the first stage DC voltage control is performed. The output of the circuit 151 is used as a lower limit value for the output of the second-stage DC voltage control circuit 152, and the output of the second-stage DC voltage control circuit 152 is finally set as the set value Idref of the active power component of the AC output current. Output to the AC current control circuit 10.

The DC voltage control circuits 151 and 152 and the active power control circuit 16 are circuits composed of, for example, a proportional-integral circuit, and have output limit values other than the upper limit value or the lower limit value described above. Is set to a fixed value determined by the rated capacity of the converter.

In the control device for the AC / DC converter configured as described above, the DC voltage set value EdpH for the DC voltage control circuit 151 of the first stage is larger than the rated voltage, and the DC voltage control circuit 152 of the second stage is used. DC voltage set value E
If a value smaller than the rated voltage is given as dpL, when the DC voltage is close to the rated value, that is, a value between EdpL and EdpH, the first-stage DC voltage control circuit 15
The output of 1 is applied to the upper limiter, and the output value of the active power control circuit 16 given as the upper limit value becomes the output of the DC voltage control circuit 151 of the first stage.

The output of the DC voltage control circuit 152 of the second stage is in a state of being applied to the lower limiter, and the DC voltage control circuit 1 of the first stage is given as the lower limit value.
The output value of 51 becomes the output of the DC voltage control circuit 152 of the second stage. Therefore, the output value of the active power control circuit 16 is finally output as Idref, and the active power is controlled to be the set value Pref. As a result, the output of the amplifier 19 becomes zero, and the DC voltage set values EdpH, E
No correction is made to dpL.

On the other hand, the DC voltage rises and the set value Edp
When it becomes larger than H, the first stage DC voltage control circuit 151
Then, switch from limiter operation to DC voltage control operation,
The control is performed so that the DC voltage detection value Ed becomes equal to the corrected set value EdpH '. On the other hand, since the second-stage DC voltage control circuit 152 remains in the lower limit limiter state, the output of the first-stage DC voltage control circuit 151 is finally output as Idref. The active power is no longer directly controlled, and a difference occurs between the set value Pref and the detected value Pa, and the DC voltage set value EdpH is corrected by this difference to obtain EdpH ', and the DC voltage control circuit 151 of the first stage Used for control. On the contrary, when the DC voltage decreases and becomes smaller than the set value EdpL, the second-stage DC voltage control circuit 152 switches from the limiter operation to the DC voltage control operation, and the DC voltage detection value Ed becomes the corrected set value EdpL ′. Control is performed so that they become equal, and this output value is finally output as Idref. The active power is no longer directly controlled, and there is a difference between the set value Pref and the detected value Pa, and the DC voltage set value EdpL is corrected by this difference to obtain EdpL ′, and the control by the second stage DC voltage control circuit 152 is performed. Used for.

When one of the plurality of converters constituting the DC power transmission system controls the DC voltage to be constant and the control circuit shown in FIG. 17 is applied to the remaining converters, the same converter as shown in FIG. Operating characteristics are obtained.

As a result, in the DC power transmission system, the converter in one place performs the DC voltage constant control, and when the control circuit shown in FIG. 17 is applied to the other converters, the converter performs the DC voltage constant control. When the active power operating point of is within the upper and lower limit values of the output, the converter maintains the DC voltage as the rated value by performing the DC voltage constant control, and the control circuit shown in FIG. 17 is applied. The remaining converters perform power interchange according to the given active power set value.
When the active power operating point of the converter that performs constant DC voltage control exceeds the upper and lower limit values of the output, or when it is stopped due to an accident, etc., it is effective in the remaining converters to which the control circuit shown in FIG. 17 is applied. By correcting the DC voltage setting value based on the difference between the power setting value and the detected value, the converter operates in such a way that the range of change in DC voltage is minimized and the sum of active power of each converter becomes zero. . According to such an embodiment, two types of DC voltage set values are corrected by the difference between the active power set value and the detected value, and the first and second stages are set so that the corrected value and the detected DC voltage are equal. The output voltage of the active power control circuit 16 is given to the upper limiter of the first-stage DC voltage control circuit 151, and the output of the first-stage DC voltage control circuit 151 is controlled. Since the lower limit value for the output of the second-stage DC voltage control circuit 152 is given, the output of the second-stage DC voltage control circuit 152 is output as the set value Idref of the active power component. If the active power operating point of the converter that controls the DC voltage exceeds the upper and lower limit values of the output due to changes, or if the converter that controls the DC voltage stops due to an accident, etc., the operating point of the DC voltage will change. Each By adjusting according to the active power operating point of the converter,
While keeping the active power close to the set value, it is possible to prevent the DC voltage from changing significantly and continue the operation.

(Thirteenth Embodiment) In the thirteenth embodiment, in order to select one output from the outputs of the active power control circuit, the first-stage and second-stage DC voltage control circuits,
This is an example in which a minimum value selection circuit and a maximum value selection circuit are used instead of using the upper and lower limiters of the DC voltage control circuit.

The multi-terminal DC power transmission system according to the thirteenth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 18 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the thirteenth embodiment.

In this DC voltage / active power control circuit, the difference between the set value Pref of the active power and the detected value Pa is added to the adders 231 and 2 via the amplifier 19 having a constant amplification factor r.
Give to 32. In the adders 231 and 232, the corrected DC voltage set values EdpH 'and EdpL' are obtained by adding the DC voltage set values EdpH and EdpL of two different values and the output of the amplifier 19, respectively. In the first-stage DC voltage control circuit 151, control is performed so that the detected DC voltage value Ed becomes equal to the corrected DC voltage set value EdpH '.
In the DC voltage control circuit 152 of the stage, the DC voltage detection value E
Control is performed so that d becomes equal to the corrected DC voltage set value EdpL '. The active power control circuit 16 controls so that the detected value Pa of active power becomes equal to the set value Pref.
The first-stage DC voltage control circuit 151, the second-stage DC voltage control circuit 152, and the active power control circuit 16 are circuits configured by, for example, a proportional-integral circuit, and upper and lower limits determined by the rated capacity of the converter. The output is limited by the limit value.

The output of the active power control circuit 16 and the output of the DC voltage control circuit 151 of the first stage are given to the minimum value selection circuit 24 to select the smaller value, and the output of the minimum value selection circuit 24 The output of the second-stage DC voltage control circuit 152 is given to the maximum value selection circuit 25, and the larger value is selected, and the output value of the maximum value selection circuit 25 is the set value Idref of the active power component of the AC output current. Is finally output as.

The output of the active power control circuit 16 is set as an upper limit value with respect to the output of the DC voltage control circuit 151 of the first stage, and the output of the DC voltage control circuit 151 of the first stage is set to the output of the DC voltage control circuit 152 of the second stage. As means for setting the lower limit value for the output, the control circuit shown in FIG. 17 is configured to use the respective values as the upper limit value and the lower limit value for the output of each control circuit, but the control circuit shown in FIG. In addition, the minimum value selection circuit 24 and the maximum value selection circuit 25 are used.

In the control device of the AC / DC converter configured as described above, the DC voltage set value EdpH for the DC voltage control circuit 151 of the first stage is larger than the rated voltage, and the DC voltage control circuit 152 of the second stage is used. DC voltage set value E
If a value smaller than the rated voltage is given as dpL, when the DC voltage is close to the rated value, that is, a value between EdpL and EdpH, the first-stage DC voltage control circuit 15
Since the output value of 1 is larger than the output value of the active power control circuit 16, the output value of the active power control circuit 16 becomes the output of the minimum value selection circuit 24. Since the output value of the second-stage DC voltage control circuit 152 is smaller than the output value of the active power control circuit 16, the output of the minimum value selection circuit 24, that is, the output value of the active power control circuit 16 is selected as the maximum value. It becomes the output of the circuit 25. Therefore, the output value of the active power control circuit 16 is finally output as Idref, and the active power is controlled to be equal to the set value Pref.

On the other hand, when the DC voltage becomes higher than the set value EdpH, the DC voltage control circuit 151 of the first stage performs DC voltage control so that the detected DC voltage value Ed becomes equal to the corrected set value EdpH '. . On the other hand, since the output of the second-stage DC voltage control circuit 152 remains small, the output of the first-stage DC voltage control circuit 151 is finally output as Idref. As a result, the active power is no longer directly controlled, so that there is a difference between the set value Pref and the detected value Pa, and the DC voltage set value EdpH is corrected by this difference to obtain EdpH ', and the first stage DC voltage control circuit 151 is obtained.
Used for control in.

On the contrary, when the DC voltage decreases and becomes smaller than the set value EdpL, the DC voltage control circuit 152 of the second stage controls the DC voltage so that the detected DC value Ed becomes equal to the corrected set value EdpL '. Is performed, and this output value is finally output as Idref. As a result, the active power is no longer directly controlled, so the set value Pref and the detected value Pa
Is generated, and the DC voltage set value EdpL is corrected by this difference to obtain EdpL ', which is used for the control in the second-stage DC voltage control circuit 152.

When one of the plurality of converters constituting the DC power transmission system shown in FIG. 1 controls the DC voltage at a constant level and the control circuit shown in FIG. 18 is applied to the remaining converters, it is shown in FIG. Similar operating characteristics to those obtained are obtained.

According to such an embodiment, the output of the active power control circuit 16 and the first-stage DC voltage control circuit 151
Even if the output of is not used as the upper limit value and the lower limit value for the output of the control circuit, it is possible to obtain the same effects as the above-described twelfth embodiment.

(Fourteenth Embodiment) The fourteenth embodiment is an example in which the correction position in the control circuit shown in FIG. 17 is shifted after the DC voltage set value and the detected value are calculated.

The multi-terminal DC power transmission system according to the fourteenth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 19 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the fourteenth embodiment.

This DC voltage / active power control circuit 70 is
The difference between the set value Pref of the active power and the detection value Pa is given to the adders 231 and 232 via the amplifier 19 having a constant amplification factor r. In the adder 231, the DC voltage set value Edp
The difference ΔEdH ′ of the DC voltage corrected by adding the output of the amplifier 19 to the difference ΔEdH between the H and the DC voltage detection value Ed is obtained. The output of 19 is added to obtain the corrected DC voltage difference ΔEdL '. The DC voltage control circuit 151 of the first stage controls so that the difference ΔEdH ′ of the corrected DC voltage becomes zero, and the DC voltage control circuit 1 of the second stage 1
At 52, control is performed so that the difference ΔEdL 'of the corrected DC voltage becomes zero. In addition, the active power control circuit 16 controls so that the detected value Pa of active power becomes equal to the set value Pref. The first-stage DC voltage control circuit 151, the second-stage DC voltage control circuit 152, and the active power control circuit 16 are control circuits configured by, for example, a proportional integration circuit. The output of the active power control circuit 16 is used as an upper limit value for the output of the first-stage DC voltage control circuit 151, and the output of the first-stage DC voltage control circuit 151 is the second-stage DC voltage control circuit 152. Is used as a lower limit value for the output of the DC voltage control circuit, and the output of the second-stage DC voltage control circuit 152 is finally output as the set value Idref of the active power component of the AC output current.

In the control device for the AC / DC converter configured as described above, a value larger than the rated voltage is set as the DC voltage set value EdpH for the first-stage DC voltage control circuit 151, and for the second-stage DC voltage control circuit 152. DC voltage set value E
If a value smaller than the rated voltage is given as dpL, when the DC voltage is close to the rated value, that is, a value between EdpL and EdpH, the first-stage DC voltage control circuit 15
The output value of 1 is larger than the output value of the active power control circuit 16, and the output of the second-stage DC voltage control circuit 152 is smaller than the output value of the active power control circuit 16. The output value of the circuit 16 finally becomes Idref
Will be output as, and the active power will be the set value Pref
Controlled to follow. As a result, the output of the amplifier 19 becomes zero, and the difference between the DC voltages ΔEdH and ΔEdL is not corrected.

On the other hand, when the DC voltage becomes larger than the set value EdpH, in the first-stage DC voltage control circuit 151, the upper limiter operation is switched to the DC voltage control operation, and the corrected DC voltage difference ΔEdH ′ becomes zero. While the control is performed, while the second-stage DC voltage control circuit 152 remains in the lower limit limiter operation, the output of the first-stage DC voltage control circuit 151 is finally output as Idref. Since the active power is no longer directly controlled, a difference occurs between the set value Pref and the detected value Pa, and this difference causes a difference Δ in the DC voltage.
EdH is corrected to obtain ΔEdH ', which is used for the control in the first-stage DC voltage control circuit 151.

On the contrary, when the DC voltage decreases and becomes smaller than the set value EdpL, the second-stage DC voltage control circuit 152 switches from the lower limiter operation to the DC voltage control operation, and the corrected DC voltage difference ΔEdL ' The control is performed so that it becomes zero, and this output value is finally output as Idref. As a result, active power is no longer directly controlled, so that a difference occurs between the set value Pref and the detected value Pa, and the difference ΔEdL of the DC voltage is corrected by this difference to obtain ΔEdL ′, and the DC voltage control circuit 152 of the second stage is obtained. Used for control in.

Therefore, when the DC voltage is controlled to be constant in one of the converters constituting the DC power transmission system as shown in FIG. 1 and the control circuit shown in FIG. 19 is applied to the remaining converters, The same operating characteristics as described with reference to FIG. 13 can be obtained.

According to such an embodiment, the difference between the two kinds of DC voltage set value and the detected value is corrected, but the same effect as the twelfth embodiment described above is obtained. Can be played.

(Fifteenth Embodiment) In the fifteenth embodiment, a DC voltage set value is corrected by a difference between an active power set value and a detected value, and a DC voltage bias is added to or subtracted from the corrected value. 2 types of set values are created to establish a control method similar to that of the twelfth embodiment.

The multi-terminal DC power transmission system according to the fifteenth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 20 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the fifteenth embodiment.

This DC voltage / active power control circuit adds the difference between the set value Pref of the active power and the detected value Pa to the DC voltage set value Edp via the amplifier 19 having a constant amplification factor r. A corrected DC voltage set value Edp 'is obtained. In the adder 261, the DC voltage set value bias amount ΔE
dp is added to the corrected DC voltage set value Edp ′ with a positive polarity, and the adder 262 adds the DC voltage set value bias amount ΔEdp.
Are added to the corrected DC voltage set value Edp 'with a negative polarity to obtain a first DC voltage set value EdpH' and a second DC voltage set value EdpL ', respectively. The first-stage DC voltage control circuit 151 performs control so that the DC voltage detection value Ed becomes equal to the first DC voltage setting value EdpH ', and the second-stage DC voltage control circuit 152 controls the DC voltage detection value Ed to The control is performed so that it becomes equal to the DC voltage set value EdpL 'of 2. Further, in the active power control circuit 16, the active power detection value Pa
Is controlled to be equal to the set value Pref. The output of the active power control circuit 16 is the DC voltage control circuit 15 of the first stage.
1 is used as an upper limit value for the output, the output of the first-stage DC voltage control circuit 151 is used as a lower limit value for the output of the second-stage DC voltage control circuit 152, and the second-stage DC voltage control is used. The output of the circuit 152 is
Finally, it is output as the set value Idref of the active power component of the AC output current.

In the control device for the AC / DC converter configured as described above, the rated voltage set value is set as the DC voltage set value Edp,
If a positive value is given as the DC voltage bias component ΔEdp, the first DC voltage setting value EdpH ′ is larger than the rated voltage,
The second set value of DC voltage EdpL 'is smaller than the rated voltage.

A value where the DC voltage is close to the rated value, that is, Edp
When operating at a value between L'and EdpH ', the output of the first-stage DC voltage control circuit 151 becomes larger than the output value of the active power control circuit 16, and the second-stage DC voltage Since the output of the control circuit 152 is smaller than the output value of the active power control circuit 16, the output value of the active power control circuit 16 is finally output as Idref,
The active power is controlled so as to be the set value Pref.
As a result, the output of the amplifier 19 becomes zero, and the DC voltage set value Edp is not corrected.

On the other hand, when the DC voltage becomes larger than the set value EdpH ', the first-stage DC voltage control circuit 151 switches from the upper limit limiter operation to the DC voltage control operation, and the DC voltage is controlled to become equal to the set value EdpH'. Is done. On the other hand, since the second-stage DC voltage control circuit 152 remains in the lower limit limiter state, the output of the first-stage DC voltage control circuit 151 is finally output as Idref. Since the active power is no longer directly controlled, the set value Pre
There is a difference between f and the detected value Pa, and this difference corrects the DC voltage set value Edp.

On the contrary, the DC voltage decreases and the set value EdpL '
When it becomes smaller, the lower limit limiter operation is switched to the DC voltage control operation in the second-stage DC voltage control circuit 152, control is performed so that it becomes equal to the DC voltage detection value EdpL ′, and this output value is finally output as Idref. To be done.
Since the active power is no longer directly controlled, a difference occurs between the set value Pref and the detected value Pa, and the difference corrects the DC voltage set value Edp.

Therefore, when one of the plurality of converters constituting the DC power transmission system as shown in FIG. 1 controls the DC voltage to be constant and the control circuit shown in FIG. 20 is applied to the remaining converters, Operation characteristics similar to those of the ninth embodiment described with reference to FIG. 13 can be obtained.

From the above results, by constructing a DC power transmission system by combining a converter equipped with the control circuit shown in FIG. 20 and a converter for performing DC voltage control, normally the DC voltage is maintained as set value. For converters other than converters that perform DC voltage control, the active power that matches the set value can be accommodated, and the active power operating point of the converter that performs DC voltage control can be changed by changing the active power set value. If the upper and lower limit values of the output are exceeded or the converter that controls the DC voltage stops due to an accident, etc., adjust the operating point of the DC voltage according to the active power operating point of each converter. As a result, it is possible to prevent the DC voltage from fluctuating significantly and continue the operation while keeping the active power close to the set value.

(Sixteenth Embodiment) In the sixteenth embodiment, the set value of the DC voltage corrected by the deviation of the active power set value is input to the DC voltage control circuit through a limiter circuit having a predetermined slope. This is an example of doing so.

The multi-terminal DC power transmission system according to the sixteenth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 21 shows the internal structure of the DC voltage / active power control circuit in the control device for the AC / DC converter provided in the DC power transmission system according to the sixteenth embodiment.

This DC voltage / active power control circuit 70 is
The difference between the active power detection value Pa and the active power setting value Pref is
The corrected DC voltage set value Edp 'is obtained by adding to the DC voltage set value Edp via the amplifier 19 having a constant amplification factor r. This DC voltage set value Edp 'is input to the limiter circuit 27 to limit the value, and the output of the limiter circuit 27 is set as the final DC voltage set value Edp ". Final DC voltage set value Edp" and DC voltage The detected value Ed is matched, and the deviation is input to the DC voltage control circuit 15 composed of, for example, a proportional-integral circuit, where the final DC voltage set value Edp ″ and the DC voltage detected value Ed become equal. The output of the DC voltage control circuit 15 is used as the set value Idref of the active power component of the AC current.The DC voltage control circuit 15 is provided with upper and lower limit values determined by the rated capacity of the converter and the like. The output Idref is limited so as not to exceed this range.

In the control apparatus for the AC / DC converter configured as described above, the active power set value Pref and the active power detection value Pa are set.
, The output of the amplifier 19 becomes zero, and the DC voltage set value Edp is not corrected. Therefore, the DC voltage becomes a value according to the given set value Edp. That is, the control is performed so that both the DC voltage and the active power have the values as the initially set values.

On the other hand, the set value Pref of the active power and the detected value P
If there is a difference in a, for example, if the detected value Pa is larger than the active power setting value Pref, the amplifier 19
Output becomes a negative value and is added to the DC voltage setting value Edp, so the corrected DC voltage setting value Edp 'becomes a smaller value than the initial setting value Edp. On the contrary, the active power setting value Pre
When the detected value Pa becomes smaller than f, the output of the amplifier 19 becomes a positive value and is added to the DC voltage set value Edp, so the corrected DC voltage set value Edp 'is larger than Edp. It becomes a value. This corrected DC voltage set value E
If dp ′ is a value within the upper and lower limit limits of the limiter circuit 27, the output Edp ″ of the limiter circuit 27 is the input value Edp ′.
Becomes equal to That is, as the detected value Pa of active power becomes larger than the set value Pref, the final DC voltage set value Edp ″ becomes smaller, and as the detected value Pa of active power becomes smaller than the set value Pref, the final value. The DC voltage set value Edp ″ has a characteristic of increasing.

The difference between the set value of the active power and the detected value becomes large, and the corrected DC voltage set value Edp 'becomes the limiter circuit 27.
When the upper and lower limit values are exceeded, the final DC voltage set value Edp ″ output from the limiter circuit 27 becomes equal to the upper limit value or the lower limit value preset in the limiter circuit 27.

FIG. 22 shows a case where each converter is controlled by the control device configured as described above in the multi-terminal DC power transmission system consisting of the three converters A, B and C shown in FIG. FIG. 6 is a characteristic diagram showing the relationship between active power and DC voltage of FIG.

Each of the three converters is equipped with the DC voltage / active power control circuit 70 of FIG. 21, and the DC voltage set value Edp is set.
The rated voltage of 100% is commonly given as. Points a, b, c, b ', c'shown in the figure are operating points of the respective converters.

Here, as the upper and lower limit values of the limiter circuit 27 in the control circuit 70, the converter A is given a sufficiently large positive and negative value, the converter B is given as Edp ± ΔEdpB, and the converter C is given as Edp ± ΔEdpC. It is assumed that the active power set values Pref A, Pref B, and Pref C are given to the respective converters.

In each converter, when the DC voltage is within the upper and lower limit values, that is, between Edp ± ΔEdp,
The characteristic is a downward-sloping characteristic in which the DC voltage decreases as the active power increases. On the other hand, when the DC voltage exceeds the upper and lower limit values, the DC voltage has a constant characteristic according to the limit value Edp ± ΔEdp.

By providing such characteristics, normally, each converter is controlled so as to have a value according to each active power set value, and the DC voltage becomes the common set value Edp, and the operating point of each converter is controlled. Are a, b, and c.

From this state, if the converter A stops due to an accident or the like, the converters B and C have a sum of active powers of zero and a direct current voltage moves to a common point b ', c'to be balanced, DC voltage is the upper limit value of converter B Edp + ΔEdp
Since it is larger than B, the converter B is in a constant DC voltage control and is controlled so that the voltage does not rise any more.

According to this embodiment, the difference between the active power detection value Pa and the active power setting value Pref is added to the DC voltage setting value Edp to obtain the corrected DC voltage setting value Edp '. The set value Edp 'is input to the limiter circuit 27 to limit the value, the output of the limiter circuit 27 is compared with the detected DC voltage Ed as the final DC voltage set value Edp ", and the deviation is DC voltage controlled. Since it is configured to be input to the circuit 15 for control, usually, each converter performs active power interchange according to a given active power set value,
In addition, the operation can be performed so that the DC voltage becomes the value as set. Furthermore, if the active power settings given to each converter become unbalanced due to an accident, such as stopping the converter or changing the active power setting, etc., each converter will share the DC voltage by adjusting the DC voltage. By absorbing the unbalanced component, it is possible to prevent the active power operating point of the specific converter from deviating largely from the set value, and to operate while preventing the DC voltage from fluctuating significantly. .

(Seventeenth Embodiment) A seventeenth embodiment is an example in which the function of the limiter circuit in the sixteenth embodiment is realized by a combination of a minimum value selection circuit and a maximum value selection circuit.

The multi-terminal DC power transmission system according to the seventeenth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 23 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the seventeenth embodiment.

This DC voltage / active power control circuit 70 is
The difference between the active power detection value Pa and the active power setting value Pref is
The corrected DC voltage set value Edp 'is obtained by adding to the DC voltage set value Edp via the amplifier 19 having a constant amplification factor r. The corrected DC voltage set value Edp 'and the upper limit value Edmax for the DC voltage set value are input to the minimum value selection circuit 24, the smaller value is selected, and the minimum value selection circuit 2 is further selected.
Lower limit value Edm for output 4 and DC voltage setting value
In is input to the maximum value selection circuit 25, and the larger value is selected and output. The output of the maximum value selection circuit 25 is set as the final DC voltage set value Edp ″. The output value Edp ″ of the maximum value selection circuit 25 is compared with the DC voltage detection value Ed,
For example, the voltage is input to the DC voltage control circuit 15 including a proportional-integral circuit, and the DC voltage control circuit 15 controls so that the final DC voltage set value Edp ″ and the DC voltage detection value Ed are equal. The output of the circuit 15 is used as the set value Idref of the active power component of the AC current.The DC voltage control circuit 15 is provided with upper and lower limit values determined by the rated capacity of the converter and the output Idref is The upper limit value Edmax is larger than the set value Edp and the lower limit value Edm is limited so as not to exceed this range.
In, a value smaller than the set value Edp is set.

In the controller of the AC / DC converter configured as described above, the active power set value Pref and the active power detected value Pa are set.
If they are equal to each other, the output of the amplifier 19 becomes zero, and the DC voltage set value is not corrected. Therefore, the DC voltage becomes a value according to the given set value Edp. That is, the control is performed such that both the DC voltage and the active power have the values as set values.

On the other hand, the set value Pref of the active power and the detected value P
When there is a difference in a, the value obtained by multiplying the difference by the amplification factor r is added to the DC voltage setting value Edp. Therefore, the DC voltage setting value becomes smaller as the active power detection value Pa increases. Will be corrected. Further, the DC voltage set value is corrected such that the DC voltage increases as the active power detection value Pa decreases. If the corrected DC voltage set value Edp ′ is a value between the upper limit value Edmax and the lower limit value Edmin, the final DC voltage set value Edp ″ output from the maximum value selection circuit 25 is the corrected DC voltage set value Edp ″. Since it becomes equal to the voltage setting value Edp ', the DC voltage is controlled to have a smaller value as the detected value of active power becomes larger and a larger value as the detected value of active power becomes smaller.

The difference between the set value of active power and the detected value becomes large, and the corrected DC voltage set value Edp 'becomes the upper limit value E.
When the value becomes larger than dmax or becomes smaller than the lower limit value Edmin, the output value of the maximum value selection circuit 25 becomes a constant value equal to the upper limit value Edmax or the lower limit value Edmin.

If a multi-terminal DC power transmission system is configured with three converters A to C controlled by the control device having the control circuit shown in FIG. 23, the characteristics of active power and DC voltage will be as shown in FIG.
It is as shown in

According to this embodiment as well, the same operational effects as those of the above-described sixteenth embodiment can be obtained.

(Eighteenth Embodiment) In the eighteenth embodiment, three kinds of DC voltage set values are provided and controlled, and the active power set value is set as a deviation between an intermediate DC voltage set value and a detected value. This is an example in which the correction is performed with a corresponding value.

Since the multi-terminal DC power transmission system according to the eighteenth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 24 shows the internal structure of the DC voltage / active power control circuit in the control device for the AC / DC converter provided in the DC power transmission system according to the eighteenth embodiment.

This DC voltage / active power control circuit is provided with three kinds of DC voltage set values Edp, EdpH and EdpL. EdpH is larger than Edp, and EdpL is smaller than Edp. DC voltage setting value Edp and DC voltage detection value Ed
Is added to the active power setting value Pref via the amplifier 20 to calculate the corrected active power setting value Pref ′, and the active power control circuit 16 calculates the active power setting value Pref ′ corrected by the active power detection value Pa. Control to be equal to.
Further, in the first-stage DC voltage control circuit 151, the DC voltage detection value Ed becomes equal to the set value EdpH, and in the second stage DC voltage control circuit 152, the DC voltage detection value Ed becomes equal to the set value EdpL. Take control. The output of the active power control circuit 16 is used as an upper limit value for the output of the first-stage DC voltage control circuit 151, and the output of the first-stage DC voltage control circuit 151 is the output of the second-stage DC voltage control circuit 152. Used as the lower limit value for
The output of the second-stage DC voltage control circuit 152 is finally output to the AC current control circuit 10 as a set value Idref of the active power component of the AC output current.

The first stage DC voltage control circuit 151,
Second stage DC voltage control circuit 152, active power control circuit 1
Reference numeral 6 is a control circuit composed of, for example, a proportional-integral circuit, and fixed output values other than the upper limit value or the lower limit value described above are set to fixed values determined by the rated capacity of the converter. .

In the control device of the AC / DC converter configured as described above, the output of the amplifier 20 becomes zero when the DC voltage setting value Edp and the detection value Ed are equal, so that the effective power control circuit 16 is supplied with the effective power. The power setting value Pref 'is equal to the initially supplied active power setting value Pref.

On the other hand, the output of the first-stage DC voltage control circuit 151 is in the state of being subjected to the upper limit limiter, and the output of the active power control circuit 16 given as the upper limit limiter value is the first-stage DC voltage control circuit. The output is 151. Further, since the output of the second-stage DC voltage control circuit 152 is in the state of being applied to the lower limiter, the output of the first-stage DC voltage control circuit 151 given as the lower limit value is the second-stage DC voltage. It becomes the output of the control circuit 152.

Therefore, the output value of the active power control circuit 16 is finally output as Idref, and the active power is controlled so as to be the set value Pref.

On the other hand, when the DC voltage Ed rises above the set value Edp, the output of the amplifier 20 is a negative value, so the active power set value Pre corrected by the output of the amplifier 20 is set.
f'is a value smaller than the initially set value Pref. Further, when the DC voltage Ed is lower than the set value Edp, the output of the amplifier 20 becomes a positive value.
The effective voltage setting value Pref 'corrected by the output of is larger than the initially set setting value Pref. In other words, the characteristic of the lower right is obtained in which the active power decreases as the DC voltage increases.

Further, when the fluctuation of the DC voltage becomes large and the DC voltage detection value Ed becomes a value larger than the DC voltage set value EdpH, the DC voltage control circuit 151 of the first stage starts the DC voltage control from the state where the upper limit is applied. Switch to 2
Since the DC voltage control circuit 152 of the first stage is still in the lower limit limiter state, the DC voltage control circuit 151 of the first stage
Output becomes the final output Idref, and the DC voltage detection value E
The d is controlled to be equal to the DC voltage set value EdpH.

On the contrary, when the detected DC voltage value Ed becomes a value smaller than the DC voltage setting value EdpL, the DC voltage control circuit 152 of the second stage switches from the state in which the lower limit is applied to the DC voltage control, and finally The output Idref is controlled so that the DC voltage detection value Ed becomes equal to the set value EdpL.

Therefore, as shown in FIG. 1, the control circuit shown in FIG. 24 is applied to each control device of a plurality of converters which constitute the DC power transmission system, and one of the converters has a sufficient DC voltage set value EdpH. By setting a large value and a sufficiently small value for EdpL, and for the remaining converters, the values shown in Fig. 22 are set for each converter by setting EdpL and EdpH that differ by about 10% from Edp. It is possible to have the same operation characteristics as.

According to such an embodiment, the output of the active power control circuit 16 is determined based on the active power set value Pref 'corrected by the difference between the direct current voltage set value Edp and the detected value Ed, and the DC voltage detected value is determined. The output of the active power control circuit 16 is used as the upper limit value of the first-stage DC voltage control circuit 151 that controls Ed to be equal to the set value EdpH, and the DC voltage detection value Ed is controlled to be equal to the set value EdpL. Since the output of the DC voltage control circuit 151 of the first stage is used as the lower limit value of the DC voltage control circuit 152 of the second stage for performing the It is possible to output and operate so that the DC voltage becomes the value as set. Furthermore, if the DC voltage fluctuates due to a converter stoppage due to an accident or a change in the active power setting value, each converter will share the active power and adjust the active power to identify the DC voltage while suppressing the fluctuation. The active power operating point of the converter can be prevented from largely deviating from the set value, and the operation can be continued while the DC voltage is prevented from largely changing.

(Nineteenth Embodiment) In the nineteenth embodiment, the minimum value selection circuit and the maximum value selection circuit are used for output selection as the set value Idref of the active power component in the eighteenth embodiment. This is an example.

The multi-terminal DC power transmission system according to the nineteenth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 25 shows the internal structure of the DC voltage / active power control circuit in the control device for the AC / DC converter provided in the DC power transmission system according to the nineteenth embodiment.

In this DC voltage / active power control circuit, the output value of the active power control circuit 16 and the output value of the first-stage DC voltage control circuit 151 are given to the minimum value selection circuit 24 and the smaller value is selected. Output value of the minimum value selection circuit 24 and 2
The output value of the DC voltage control circuit 152 of the stage is given to the maximum value selection circuit 25 and the larger value is selected, and the output of the maximum value selection circuit 25 is finally set as the set value Idref of the active power component of the AC output current. It is configured to be output as an output. The other structure is similar to that of the eighteenth embodiment.

In the controller of the AC / DC converter configured as described above, the output of the amplifier 20 becomes zero when the DC voltage set value Edp and the detected value Ed are equal, and the active power control circuit 1
The corrected active power setting value Pref 'given to No. 6 becomes equal to the initially applied active power setting value Pref. On the other hand, since the output of the first-stage DC voltage control circuit 151 has a large value, the minimum value selection circuit 24 selects the output of the active power control circuit 16. Since the output of the second-stage DC voltage control circuit 152 has a small value, the maximum value selection circuit 25 selects the output of the minimum value selection circuit 24, that is, the output of the active power control circuit 16. Therefore, the output value of the active power control circuit 16 is finally output as Idref, and the active power is controlled to be the set value Pref.

On the other hand, when the DC voltage changes from the set value Edp, the corrected active power set value Pref 'changes from the initially given set value Pref, and the active power decreases as the DC voltage rises. The characteristics are obtained. When the DC voltage fluctuation further increases and the DC voltage detection value Ed becomes a value larger than the DC voltage setting value EdpH, the DC voltage control circuit 151 of the first stage switches from the state in which the upper limit is applied to the DC voltage control to the one stage. The output of the eye DC voltage control circuit 151 becomes the final output Idref, and the DC voltage detection value Ed is controlled to be equal to the DC voltage setting value EdpH. On the contrary, when the DC voltage detection value Ed becomes smaller than the DC voltage setting value EdpL, the second-stage DC voltage control circuit 152 switches from the state of the lower limit limiter to the DC voltage control, and the final output Idref becomes The DC voltage detection value Ed is controlled to be equal to the DC voltage set value EdpL.

Therefore, if a plurality of converters constituting the DC power transmission system are controlled by the control device having the control circuit shown in FIG. 25, one of the converters has a sufficient DC voltage set value EdpH. Set a large value and a sufficiently small value as EdpL, and set EdpL and EdpL for the remaining converters.
When H is set to a value having a difference of about 10% from the DC rated voltage, the same operating characteristics as those described with reference to FIG. 22 can be obtained.

According to this embodiment as well, the same operational effects as those of the above-described eighteenth embodiment can be obtained.

(Twentieth Embodiment) The twentieth embodiment is an example in which the correction position of the active power set value in the eighteenth embodiment is changed.

The multi-terminal DC power transmission system according to the twentieth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 26 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the twentieth embodiment.

This DC voltage / active power control circuit calculates the difference ΔP between the active power set value Pref and the active power detection value Pa by
The difference between the DC voltage set value Edp and the DC voltage detection value Ed is added to correct the output of the amplifier 20, and the active power control circuit 16 controls so that the corrected active power difference ΔP ′ becomes zero. To do. The other structure is the 18th shown in FIG.
It is the same as the control circuit in the embodiment.

The control device for the AC / DC converter configured as described above controls a plurality of converters constituting the DC transmission system, and one of the converters has a sufficiently large DC voltage set value EdpH. , EdpL are set to sufficiently small values, and in the remaining converters, if EdpL and EdpH are set to values that differ by about 10% from the DC rated voltage, operating characteristics similar to those described in FIG. 22 are obtained. To be

According to such an embodiment, normally, each converter can output according to the given active power set value, and can operate at the DC voltage according to the set value. Furthermore, if the DC voltage fluctuates due to a converter stoppage due to an accident or a change in the active power setting value, each converter will share the active power and adjust the active power to identify the DC voltage while suppressing the fluctuation. The active power operating point of the converter can be prevented from largely deviating from the set value, and the operation can be continued while the DC voltage is prevented from largely changing.

(Twenty-first Embodiment) In the twenty-first embodiment, three kinds of DC voltage set values are set, and the intermediate value of the DC voltage set values is corrected by the difference between the active power set value and the detected value. ,
This is an example in which one output is selected from three DC current control circuits.

The multi-terminal DC power transmission system according to the twenty-first embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 27 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the twenty-first embodiment.

This DC voltage / active power control circuit sets the active power set value Pref and the DC voltage set values Edp, EdpH and EdpL of three different values. EdpH is Edp
A larger value, EdpL, is a smaller value than Edp. The difference between the active power setting value Pref and the active power detection value Pa is passed through the amplifier 19 having a constant amplification factor r to set the DC voltage setting value Edp.
To calculate the corrected DC voltage set value Edp '.
The first-stage DC voltage control circuit 151 performs control so that the detected value Ed becomes equal to the corrected DC voltage set value Edp '. On the other hand, in the second-stage DC voltage control circuit 152, control is performed so that the detected DC voltage value Ed becomes equal to the large DC voltage set value EdpH, and the third-stage DC voltage control circuit 15 is controlled.
In 3, the control is performed so that the detected value Ed of the DC voltage becomes equal to the set value EdpL of the DC voltage having a small value. The output of the DC voltage control circuit 151 of the first stage is the DC voltage control circuit 15 of the second stage.
2 is used as an upper limit value, and the output of the second-stage DC voltage control circuit 152 is the third-stage DC voltage control circuit 15
It is used as the lower limit value of 3, and the output of the DC voltage control circuit 153 at the third stage is given to the AC current control circuit 10 as the final output Idref.

In the control device for an AC / DC converter configured as described above, the output of the amplifier 19 becomes zero when the detected value Pa of active power is operating at the value according to the set value Pref. The direct-current voltage control circuit 151 controls the direct-current voltage so that it keeps a value according to the initially set value Edp. In the second-stage DC voltage control circuit 152, the set value EdpH
Is larger than the detected value Ed, the upper limiter operation is performed, and the set value EdpL is set in the third-stage DC voltage control circuit 153.
Is smaller than the detected value Ed, the lower limit limiter operation is performed. As a result, the output of the first-stage DC voltage control circuit 151 is finally output as Idref.

On the other hand, when the detected value Pa of active power becomes a value larger than the set value Pref, the output of the amplifier 19 becomes a negative value, so the corrected DC voltage set value Edp '
Is smaller than the initially set value Edp. On the contrary, when the detected value Pa of active power becomes smaller than the set value Pref, the output of the amplifier 19 becomes a positive value, so the corrected DC voltage set value Edp 'is larger than the initial set value Edp. It becomes a value. Thereby, the DC voltage is controlled to change according to the operating value of the active power, and when the value becomes larger than the set value EdpH, the second-stage DC voltage control circuit 152 switches from the limiter operation to the DC voltage control operation, The DC voltage detection value Ed is controlled to be constant so as to be equal to the set value EdpH.

Further, the detected DC voltage value Ed is the set value EdpL.
When it becomes smaller, the DC voltage control circuit 153 of the third stage switches from the limiter operation to the DC voltage control operation, and the DC voltage detection value Ed is controlled so as to be equal to the set value EdpL.

Therefore, the control circuit shown in FIG. 27 is applied to a plurality of converters constituting the DC power transmission system, and one converter has a sufficiently large DC voltage set value EdpH, Ep.
Give a sufficiently small value for dpL, and Edp for the remaining converters.
When L and EdpH are given values that differ by about 10% from the DC rated voltage, the same operating characteristics as those described with reference to FIG. 22 are obtained.

According to such an embodiment, three kinds of DC voltage set values are set, the intermediate value of the DC voltage set values is corrected by the difference between the active power set value and the detected value, and the first stage DC is set. The output of the voltage control circuit 151 is the DC voltage control circuit 1 of the second stage.
It is used as the upper limit value of 52, and the output of the DC voltage control circuit 152 of the second stage is the DC voltage control circuit 15 of the third stage.
Since it is used as the lower limit value of 3 and one output is selected from among three DC current control circuits, each converter normally outputs an output according to the given active power set value, and The operation can be performed with the voltage according to the set value. Furthermore, if the active power set value given to each converter becomes unbalanced due to the stop of the converter or the change of the active power set value due to an accident, the DC voltage is adjusted and each converter takes charge. By absorbing the imbalance,
It is possible to prevent the active power operating point of the specific converter from largely deviating from the set value, and to prevent the DC voltage from greatly changing to continue the operation.

(Twenty-second Embodiment) A twenty-second embodiment is an example in which a minimum value selection circuit and a maximum value selection circuit are specified for selecting the final output in the twenty-first embodiment.

Since the multi-terminal DC power transmission system according to the 22nd embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 28 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the 22nd embodiment.

In this DC voltage / active power control circuit, the output of the DC voltage control circuit 151 is set to the upper limit value with respect to the output of the DC voltage control circuit 152 of the second stage, and the output of the DC voltage control circuit 152 of the second stage is set to 3 times. DC voltage control circuit 153 of the third stage
As a means for setting the lower limit value of, the output of the first-stage DC voltage control circuit 151 and the output of the second-stage DC voltage control circuit 152 are input to the minimum value selection circuit 24, and the smaller value is selected, Value selection circuit 24 and third stage DC voltage control circuit 1
The output of 53 is input to the maximum value selection circuit 25, the larger value is selected, and the output of the maximum value selection circuit 25 is the final output. The other structure is the same as that of the 21st embodiment.

The control device for the AC / DC converter configured as described above is applied to control the plurality of converters constituting the DC power transmission system, and the DC voltage set value E is applied to one converter.
If dpH is set to a sufficiently large value and EdpL is set to a sufficiently small value, and in the remaining converters, EdpL and EdpH are given values that differ by about 10% from the DC rated voltage, respectively, the same as that explained in FIG. The operating characteristics of are obtained.

According to such an embodiment, the same operational effects as those of the 21st embodiment can be obtained.

(Twenty-third Embodiment) The twenty-third embodiment is an example in which the correction position for the DC voltage set value in the twenty-first embodiment is changed after the difference between the DC voltage set value and the detected value is calculated. is there.

The multi-terminal DC power transmission system according to the twenty-third embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 29 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the 23rd embodiment.

This DC voltage / active power control circuit adds the output of the amplifier 19 to the difference ΔEd between the DC voltage setting value Edp and the DC voltage detection value Ed to correct the difference Δ in the corrected DC voltage.
Ed 'is obtained, and the first-stage DC voltage control circuit 151 is controlled so that the corrected DC voltage difference ΔEd' becomes zero. The other configuration is the same as that of the control circuit of the twenty-first embodiment.

With the control device for AC / DC converters configured as described above, a plurality of converters constituting the DC power transmission system are controlled, and one converter sets the DC voltage set value E.
If a sufficiently large value is given as dpH and a sufficiently small value is given as EdpL, and the remaining converters are provided with EdpL and EdpH that are different by about 10% from the DC rated voltage, respectively, the same as that explained in FIG. Operating characteristics are obtained.

According to such an embodiment, since the plurality of exchangers constituting the DC power transmission system are controlled by the controller of the exchanger having the control circuit shown in FIG. 29, the twenty-first embodiment is realized. It is possible to obtain the same operational effect as that of the above embodiment.

(Twenty-fourth Embodiment) In the twenty-fourth embodiment, the difference between the active power set value and the detected value is added to the DC voltage set value through the dead band circuit to correct it, and the corrected DC voltage set value is limited. This is an example of inputting to a DC voltage control circuit through a circuit.

Since the multi-terminal DC power transmission system according to the twenty-fourth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 30 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the twenty-fourth embodiment.

This DC voltage / active power control circuit detects the difference between the set value Pref of active power and the detected value Pa as the dead zone circuit 1.
8 and the amplifier 19 to obtain a corrected DC voltage set value Edp 'by adding it to the DC voltage set value Edp, and input the corrected DC voltage set value Edp' to the limiter circuit 27 to limit the DC voltage setting. The value Edp ″ is obtained. The Edp ″ thus obtained and the DC voltage detection value Ed are compared and input to the DC voltage control circuit 15 composed of, for example, a proportional-integral circuit, and the DC voltage control circuit 15 detects the DC voltage. Value E
Control is performed so that d becomes equal to the limited DC voltage set value Edp ″.

In the controller of the AC / DC converter configured as described above, assuming that the dead range of the dead zone circuit 18 is ± ΔPref and the upper and lower limit values of the limiter circuit 27 are Edp ± ΔEdp, the direct current as shown in FIG. The characteristics of voltage and active power are obtained. That is, the operating value of active power is the set value Pref
Within the range of ± ΔPref, the DC voltage is set to E
The control value is kept constant as dp, and the operating value of active power is Pref ±
When the value is out of the range of ΔPref, the DC voltage setting value Edp is corrected according to the magnitude of the detected value of active power, and the characteristic becomes a downward-sloping or upward-sloping characteristic. Corrected DC voltage set value Edp '
Is beyond the range of Edp ± ΔEdp, the final DC voltage setting value Edp ″ is limited by the limiter circuit 27, and constant DC voltage control is performed so that the DC voltage becomes Edp + ΔEdp or Edp−ΔEdp.

According to such an embodiment, normally, the DC voltage is controlled to be constant according to the set value, and when the unbalanced portion of the active power of the entire DC transmission system becomes large,
By adjusting the value of the DC voltage, each converter shares and compensates the unbalanced part of the active power, thereby preventing the active power from largely deviating from the set value in the specific converter, and The operation can be performed so that the operation value does not fluctuate from the set value over a certain range.

(Twenty-fifth Embodiment) In the twenty-fifth embodiment, not the difference between the active power set value and the detected value, but the active power detected value is directly input to the dead zone circuit in the twenty-fourth embodiment. This is an example of doing so.

The multi-terminal DC power transmission system according to the twenty-fifth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 32 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the 25th embodiment.

This DC voltage / active power control circuit adds the detected active power value Pa to the DC voltage set value Edp via the dead zone circuit 18 and the amplifier 19 with a negative sign, and outputs the corrected DC voltage set value Edp '. obtain. The corrected DC voltage setting value Edp 'is input to the limiter circuit 27 to obtain the limited DC voltage setting value Edp ", and Edp" and the DC voltage detection value Ed are matched and input to the DC voltage control circuit 15. The DC voltage control circuit 15 controls the DC voltage detection value Ed to be equal to the limited DC voltage set value Edp ″.

In the controller of the AC / DC converter configured as described above, assuming that the dead range of the dead zone circuit 18 is P1 to P2 and the upper and lower limit values of the limiter circuit 27 are Edp ± ΔEdp, as shown in FIG. The characteristics of DC voltage and active power are obtained. That is, within the range of the operating values P1 to P2 of active power, the DC voltage is controlled to be constant according to the set value Edp,
When the operating value of the active power is out of the range of P1 to P2, the DC voltage set value Edp is corrected according to the magnitude of the detected value of the active power, and the characteristic becomes a downward slope or a upward slope. When the corrected DC voltage set value Edp 'exceeds the range of Edp ± ΔEdp, the limiter circuit 27 causes the final DC voltage set value Ed to be reached.
Since p ″ is limited, the DC voltage constant control is performed so that the DC voltage becomes Edp + ΔEdp or Edp−ΔEdp.

According to this embodiment, the active power detection value Pa is added via the dead zone circuit 18 and the amplifier 19 to the DC voltage set value Edp with a negative sign to obtain the corrected DC voltage set value Edp '. Since the limited direct current voltage set value Edp ″ is input to the limiter circuit 27 and the detected direct current voltage value Ed is matched, the direct current voltage is normally controlled to be constant according to the set value, and the entire direct current transmission system is controlled. When the unbalanced portion of the active power becomes large, each converter shares the unbalanced portion of the active power by adjusting the value of the DC voltage. It is possible to prevent the limiter operation from being exceeded beyond the output limit and to perform the operation so as not to fluctuate more than a certain range from the DC voltage operation value.

(Twenty-sixth Embodiment) A twenty-sixth embodiment is an example in which the function of the limiter circuit in the twenty-fourth embodiment is realized by a combination of a minimum value selection circuit and a maximum value selection circuit.

FIG. 34 is a control block diagram showing the internal structure of the DC voltage / active power control circuit applied to the control device for the AC / DC converter in the twenty-sixth embodiment.

In the twenty-sixth embodiment, the difference between the set value Pref of the active power and the detected value Pa is added to the DC voltage set value Edp via the dead zone circuit 18 and the amplifier 19, and the corrected DC voltage set value Edp '. To get The corrected DC voltage set value Edp 'and the upper limit value Edmax for the DC voltage set value are input to the minimum value selection circuit 24, the smaller value is selected and output, and the output of the minimum value selection circuit 24 and the DC voltage The lower limit value Edmin for the set value is input to the maximum value selection circuit 25, and the larger value is selected and output. DC voltage control circuit 1
5, the control is performed so that the DC voltage detection value Ed becomes equal to the final DC voltage set value Edp ″ which is the output value of the maximum value selection circuit 25, and the output is Idref as the AC current control circuit 10 of FIG. Given to.

In the control device for the AC / DC converter configured as described above, the dead range of the dead zone circuit 18 is ± ΔPref, the upper limit Edmax for the DC voltage set value is Edp + ΔEdp, and the lower limit Edmin for the DC voltage set value is Edp−. If ΔEdp is set, the characteristics of the DC voltage and the active power as shown in FIG. 31 can be obtained as in the case of using the control circuit of the twenty-fourth embodiment. That is, the DC voltage is controlled to be constant according to the set value Edp within the range of ± ΔPref with respect to the operating value set value Pref of the active power, and the operating value of the active power is Pref ± ΔPref.
When the value goes out of the range, the DC voltage set value Edp is corrected according to the magnitude of the active power detection value, and the characteristic becomes a downward rightward or upward leftward characteristic. When the corrected DC voltage setting value Edp 'becomes larger than the upper limit value Edmax = Edp + ΔEdp or becomes smaller than the lower limit value Edmin = Edp−ΔEdp, the output value Edp ″ of the maximum value selection circuit 25 becomes equal to Edmax or Edmin. , DC voltage is Edp + ΔEdp or Edp-
DC voltage constant control is performed so that ΔEdp is achieved.

According to such an embodiment also, the 24th
It is possible to obtain the same effects as those of the embodiment described above.

(Twenty-seventh Embodiment) The multi-terminal DC power transmission system according to the twenty-seventh embodiment has the same system configuration as the DC power transmission system shown in FIG. / The active power control circuit will be described in detail.

FIG. 35 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the 27th embodiment.

This DC voltage / active power control circuit is provided with DC voltage set values Edp, EdpH, and EdpL of three different values. The set value EdpH is a value larger than Edp, and EdpL is EdpL.
Use a smaller value. DC voltage setting value Edp and detection value E
The difference of d is added to the active power setting value Pref via the dead zone circuit 22 and the amplifier 20 having a constant amplification factor K to obtain a corrected active power setting value Pref '. The active power control circuit 16 performs control so that the active power detection value Pa becomes equal to the corrected active power set value Pref '. The first-stage DC voltage control circuit 151 performs control so that the DC voltage detection value Ed becomes equal to the DC voltage setting value EdpH, and the second-stage DC voltage control circuit 152 sets the DC voltage detection value Ed to the DC voltage setting value. The control is performed so that it becomes equal to the value EdpL. Then, the output of the active power control circuit 16 is used as an upper limit value for the output of the first-stage DC voltage control circuit 151, and the output of the first-stage DC voltage control circuit 151 is used as the second-stage DC voltage control circuit 152. Is used as the lower limit value for the output of the DC voltage control circuit, and the output of the DC voltage control circuit 152 of the second stage is given to the AC current control circuit 10 as the final output Idref.

The first stage DC voltage control circuit 151,
Second stage DC voltage control circuit 152, active power control circuit 1
Reference numeral 6 denotes a control circuit composed of, for example, a proportional-integral circuit. As the output limit value other than the upper limit value or the lower limit value described above, a fixed value determined from the rated capacity of the converter is set. There is.

In the control device for the AC / DC converter configured as described above, when the dead range of the dead zone circuit 22 is ± ΔEdp, the characteristics of the DC voltage and active power as shown in FIG. 36 are obtained. That is, when the operating point of the DC voltage is within the range of ± ΔEdp with respect to the DC voltage set value Edp, the active power is set to the set value Pre.
When the DC voltage is controlled to be constant as f, and the DC voltage is out of the range of Edp ± ΔEdp, the active power setting value Pref is corrected according to the magnitude of the DC voltage detection value, and the characteristic becomes a downward-sloping or upward-sloping characteristic.

Further, when the operating point of the DC voltage is lower than the DC voltage setting value EdpL of a small value or is higher than the DC voltage setting value EdpH of a large value, the DC voltage is equal to the setting value EdpL or EdpH. Control to be constant.

According to such an embodiment, three different kinds of DC voltage set values are provided, and the DC voltage set value Edp is set.
And the detected value Ed are added to the active power setting value Pref via the dead zone circuit 22, and the corrected active power setting value Pref is corrected.
′ Is used as the upper limit value of the first-stage DC voltage control circuit 151, which controls the output of the first-stage DC voltage control circuit 151 to control the output of the first-stage DC voltage control circuit 151. Is used as the lower limit value for the output of the second-stage DC voltage control circuit 152, and
The output of the DC voltage control circuit 152 at the stage is the final output I
Since it is set to dref, power is normally exchanged according to the given active power setting value, and when the DC voltage fluctuation becomes large, it is effective by correcting the active power setting value by the DC voltage fluctuation. The power can be controlled so that it does not deviate significantly from the set value and the fluctuation of the DC voltage is suppressed, and if the DC voltage fluctuation becomes large, the DC voltage can be controlled to a constant level by drastically reducing the DC voltage. It is possible to drive while preventing a rise.

(Twenty-eighth Embodiment) A twenty-eighth embodiment is an example in which the correction position of the active power set value in the twenty-seventh embodiment is calculated after the difference between the active power set value and the detected value is calculated.

Since the multi-terminal DC power transmission system according to the twenty-eighth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 37 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the 28th embodiment.

This DC voltage / active power control circuit uses the amplifier 2 to calculate the difference ΔP between the set value Pref of the active power and the detection value Pa.
The outputs of 0 are added to obtain the corrected active power difference ΔP ′. The active power control circuit 16 controls the corrected active power difference ΔP ′ to be zero. Other configurations are second
This is the same as the control circuit according to the seventh embodiment.

In the control apparatus for an AC / DC converter configured as described above, assuming that the dead range of the dead zone circuit 22 is ± ΔEdp, the same DC voltage and active power as in the twenty-seventh embodiment as shown in FIG. The characteristics of are obtained. That is, when the operating point of the DC voltage is within the range of ± ΔEdp with respect to the DC voltage set value Edp, the active power is controlled to be constant according to the set value Pref, and when the DC voltage is out of the range of Edp ± ΔEdp, the DC voltage is changed. The active power setting value Pref is corrected according to the magnitude of the detected value, and the characteristic becomes a downward-sloping or upward-sloping characteristic. further,
When the fluctuation of the DC voltage becomes large and the detected DC voltage value Ed is lower than the small DC voltage setting value EdpL or is higher than the large DC voltage setting value EdpH, the DC voltage is set to the setting value EdpL or It is controlled so as to be equal to EdpH.

According to such an embodiment also, the 27th
It is possible to obtain the same effects as those of the embodiment described above.

(Twenty-ninth Embodiment) The thirty-ninth embodiment uses the output of the active power control circuit as the upper limit value of the direct current control circuit of the first stage in the twenty-eighth embodiment, and The output of the first-stage DC current control circuit is used as the lower limit value of the second-stage DC current control circuit, but the same function was realized by combining the minimum value selection circuit and the maximum value selection circuit. is there.

The multi-terminal DC power transmission system according to the twenty-ninth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 38 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the 29th embodiment.

This DC voltage / active power control circuit outputs the output of the active power control circuit 16 to the DC voltage control circuit 1 of the first stage.
The output of the active power control circuit 16 and the first stage are used as means for setting the upper limit for the output of 51 and the output of the first-stage DC voltage control circuit 151 for the lower limit of the output of the second-stage DC voltage control circuit 152. The output of the DC voltage control circuit 151 is input to the minimum value selection circuit 24, the smaller value is selected and output, and the output of the minimum value selection circuit 24 and the output of the second-stage DC voltage control circuit 152 are set to the maximum value. The configuration is such that it is input to the selection circuit 25 and the larger value is selected and output. The other configuration is the same as that of the control circuit of the twenty-eighth embodiment.

In the control apparatus for an AC / DC converter configured as described above, if the dead range of the dead zone circuit 22 is ± ΔEdp, the same DC voltage and active power characteristics as shown in FIG. 36 are obtained. That is, when the operating point of the DC voltage is within the range of ± ΔEdp with respect to the DC voltage set value Edp, the active power is controlled to be constant according to the set value Pref, and the DC voltage is Edp ± ΔE.
If dp is out of the range, the active power setting value Pref is corrected according to the magnitude of the detected value of the DC voltage, and the characteristic becomes downward rightward or upward leftward. Furthermore, when the operating point of the DC voltage is lower than the DC voltage setting value EdpL of a small value or is higher than the DC voltage setting value EdpH of a large value,
The DC voltage setting value is controlled to be equal to EdpL or EdpH.

According to such an embodiment, the same effects as those of the above-mentioned twenty-eighth embodiment can be obtained.

(Thirtieth Embodiment) FIG. 39 shows a thirtieth embodiment.
FIG. 3 is a control block diagram showing a partial configuration of the DC power transmission system according to the embodiment of the present invention and showing an internal configuration of a DC voltage / active power control circuit in a control device for an AC / DC exchanger.

The multi-terminal DC power transmission system according to the thirtieth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

This DC voltage / active power control circuit is provided with DC voltage set values Edp, EdpH, and EdpL of three different values. The set value EdpH is larger than Edp, and EdpL is EdpL.
Set a smaller value. A value through the dead zone circuit 18 for the difference between the set value Pref and the detection value Pa of active power, and a value through the amplifier 20 having a constant amplification factor K for the difference between the DC voltage detection value Ed and the set value Edp. Is calculated and the active power control circuit 16 controls so that the output of the dead zone circuit 18 and the output of the amplifier 20 become equal.

On the other hand, the first stage DC voltage control circuit 151
Then, the DC voltage detection value Ed is controlled to be equal to the DC voltage set value EdpH, and the DC voltage control circuit 15 of the second stage is controlled.
In 2, the control is performed so that the DC voltage detection value Ed becomes equal to the DC voltage set value EdpL. With respect to the output of each control circuit thus obtained, the output of the active power control circuit 16 is used as an upper limit value for the output of the first-stage DC voltage control circuit 151, and the output of the first-stage DC voltage control circuit 151 is used. It is used as a lower limit value for the output of the second-stage DC voltage control circuit 152, and the output of the second-stage DC voltage control circuit 152 is given to the AC current control circuit 10 as the final output Idref.

In the control device for the AC / DC converter configured as described above, the dead range of the dead zone circuit 18 is ± ΔPref, the value of the DC voltage setting value EdpH is Edp + ΔEdp, and the value of the DC voltage setting value EdpL is Edp-ΔEdp. When set, characteristics of DC voltage and active power as shown in FIG. 31 are obtained. That is, when the operating value of active power is within the range of ± ΔPref with respect to the active power set value Pref, the DC voltage is controlled to be constant according to the set value Edp. The operating value of the DC voltage changes according to the magnitude of the detected power value, resulting in a characteristic of falling to the right or rising to the left. When the DC voltage exceeds the range of Edp ± ΔEdp, the DC voltage constant control is performed so that the DC voltage becomes Edp + ΔEdp or Edp−ΔEdp.

According to such an embodiment, by applying the control circuit shown in FIG. 39 to the controller of the AC / DC converter, normally the DC voltage is controlled to be constant according to the set value,
When the unbalanced portion of the active power of the entire DC transmission system becomes large, each converter shares the unbalanced portion and compensates for the unbalanced portion.
As a result, it is possible to prevent the active power from largely deviating from the set value in the specific converter, and to perform the operation so that the DC voltage operation value does not vary from the set value by a certain range or more.

(Thirty-first Embodiment) FIG. 40 shows the internal structure of the DC voltage / active power control circuit in this embodiment.

Since the multi-terminal DC power transmission system according to the thirty-first embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

In the thirty-first embodiment, the output of active power control circuit 16 in the thirtieth embodiment is set to the upper limit value for the output of first-stage DC voltage control circuit 151, 1
The output of the active voltage control circuit 16 and the output of the first stage DC voltage control circuit 151 are used as the lower limit value for the output of the second stage DC voltage control circuit 152. The output of 151 is input to the minimum value selection circuit, and the output of the minimum value selection circuit and the output of the second-stage DC voltage control circuit 152 are input to the maximum value selection circuit.

That is, the output of the active power control circuit 16 and the output of the first-stage DC voltage control circuit 151 are input to the minimum value selection circuit 24, the smaller value is selected and output, and the minimum value selection circuit 24 outputs. Output and second stage DC voltage control circuit 152
The output of is input to the maximum value selection circuit 25, and the larger value is selected and output. The other configuration is the same as that of the control circuit of the thirtieth embodiment.

In the controller of the AC / DC converter configured as described above, the dead range of the dead zone circuit 18 is ± ΔPref, the value of the DC voltage setting value EdpH is Edp + ΔEdp, and the value of the DC voltage setting value EdpL is Edp-ΔEdp. When set, characteristics of DC voltage and active power as shown in FIG. 31 are obtained. That is, the operating point of the DC voltage controls the active power to be constant as the set value Edp within the range of ± ΔPref with respect to the set value Pref, and the operating value of the active power is Pref ± ΔPref.
When the value goes out of the range, the DC voltage set value Edp is corrected according to the magnitude of the detected value of active power, and the characteristic becomes a downward rightward or upward leftward characteristic. When the DC voltage exceeds the range of Edp ± ΔEdp, the DC voltage constant control is performed so that the DC voltage becomes Edp + ΔEdp or Edp−ΔEdp.

According to such an embodiment also, the 30th
Since the operation characteristics similar to those of the embodiment of the present invention are realized, normally, the DC voltage is controlled to be constant according to the set value, and when the unbalanced portion of the active power of the entire DC transmission system becomes large, each conversion The unbalanced component is shared by the converter to prevent the active power from largely deviating from the set value in the specified converter, and the DC voltage operation value does not fluctuate from the set value beyond a certain range. You can drive.

(32nd Embodiment) FIG. 41 shows the 32nd embodiment.
FIG. 3 is a control block diagram showing a partial configuration of the DC power transmission system according to the embodiment of the present invention and showing an internal configuration of a DC voltage / active power control circuit in a control device for an AC / DC exchanger.

The multi-terminal DC transmission system according to the thirty-second embodiment has the same system configuration as the DC transmission system shown in FIG.
The active power control circuit will be described in detail.

This DC voltage / active power control circuit is provided with DC voltage set values Edp, EdpH and EdpL of three different values. The set value EdpH is larger than Edp and EdpL is EdpL.
Set a smaller value. The difference between the set value Pref of the active power and the detected value Pa is added to the DC voltage set value Edp through the dead zone circuit 18 and the amplifier 19 having a constant amplification factor r to obtain a corrected DC voltage set value Edp '. In the first-stage DC voltage control circuit 151, control is performed so that the DC voltage detection value Ed becomes equal to the corrected DC voltage set value Edp '.
In the second-stage DC voltage control circuit 152, the DC voltage detection value E
The d is controlled to be equal to the DC voltage setting value EdpH, and the third-stage DC voltage control circuit 153 controls the DC voltage detection value Ed to be equal to the DC voltage setting value EdpL. Regarding the output of each control circuit thus obtained, 1
The output of the DC voltage control circuit 151 of the second stage is used as an upper limit value for the output of the DC voltage control circuit 152 of the second stage, and the output of the DC voltage control circuit 152 of the second stage is used as the DC voltage control circuit of the third stage. The output of the third-stage DC voltage control circuit 153 is used as an upper limit value for the output of the AC current control circuit 153, and the output of the third-stage DC voltage control circuit 153 is used as the final output Idref.
Give to.

In the control device for the AC / DC converter configured as described above, the dead range of the dead zone circuit 18 is ± ΔPref, the value of the DC voltage set value EdpH is Edp + ΔEdp, and the value of the DC voltage set value EdpL is Edp-ΔEdp. When set, characteristics of DC voltage and active power as shown in FIG. 31 are obtained. That is, when the operating value of active power is within the range of ± ΔPref with respect to the active power set value Pref, the DC voltage is controlled to be constant according to the set value Edp, and it is effective when the operating value of active power is out of the range of Pref ± ΔPref. The DC voltage set value Edp is corrected according to the magnitude of the detected power value, and the characteristic becomes a downward-sloping or upward-sloping characteristic. When the DC voltage exceeds the range of Edp ± ΔEdp,
The constant DC voltage is controlled so that the DC voltage becomes Edp + ΔEdp or Edp−ΔEdp.

According to such an embodiment, by using the control circuit shown in FIG. 41, normally, the DC voltage is controlled to be constant according to the set value, and the unbalanced portion of the active power of the entire DC transmission system is normally controlled. When the power becomes large, the converters share and compensate for the unbalanced component, thereby preventing the active power from deviating significantly from the set value in the specific converter and setting the DC voltage operating value. The operation can be performed so that the value does not fluctuate beyond a certain range.

(Thirty-third Embodiment) In the thirty-third embodiment, the output of the dead band circuit is corrected before the difference between the DC voltage set value and the detected value is calculated in the thirty-second embodiment. On the other hand, in this example, the difference between the DC voltage set value and the detected value is calculated, and then the DC voltage set value is corrected by the output of the dead zone circuit.

FIG. 42 shows a partial configuration of a DC power transmission system according to the 33rd embodiment, and is a control block diagram showing an internal configuration of a DC voltage / active power control circuit in a control device for an AC / DC exchanger. Is.

The multi-terminal DC power transmission system according to the thirty-third embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

This DC voltage / active power control circuit uses the amplifier 1 to calculate the difference ΔEd between the set value Edp of the DC voltage and the detected value Ed.
The outputs of 9 are added to obtain a corrected DC voltage difference ΔEd ′, and control is performed so that the DC voltage difference ΔEd ′ corrected by the first-stage DC voltage control circuit 151 becomes zero. The other structure is the same as that of the control circuit according to the thirty-second embodiment.

In the controller of the AC / DC converter configured as described above, the dead range of the dead zone circuit 18 is ± ΔPref, the value of the DC voltage set value EdpH is Edp + ΔEdp, and the value of the DC voltage set value EdpL is Edp-ΔEdp. When set, characteristics of DC voltage and active power as shown in FIG. 31 are obtained. That is, when the operating value of active power is within the range of ± ΔPref with respect to the active power set value Pref, the DC voltage is controlled to be constant according to the set value Edp, and it is effective when the operating value of active power is out of the range of Pref ± ΔPref. The operating value of the DC voltage changes according to the magnitude of the detected power value, resulting in a characteristic of falling to the right or rising to the left. When the DC voltage exceeds the range of Edp ± ΔEdp, the DC voltage constant control is performed so that the DC voltage becomes Edp + ΔEdp or Edp−ΔEdp.

According to such an embodiment also, the 32nd
It is possible to obtain the same effects as those of the embodiment described above.

(Thirty-fourth Embodiment) In the thirty-fourth embodiment, the output of the first-stage DC voltage control circuit 151 in the thirty-second embodiment is changed to the second-stage DC voltage control circuit 152.
Upper limit value for the output of the second stage DC voltage control circuit 152 is used as the upper limit value for the output of the third stage DC voltage control circuit 153, the minimum value selection circuit and the maximum value selection This is an example in which similar functions are provided by combining circuits.

FIG. 43 shows a part of the configuration of the DC power transmission system according to the 34th embodiment, and is a control block diagram showing the internal configuration of the DC voltage / active power control circuit in the controller of the AC / DC exchanger. Is.

The multi-terminal DC power transmission system according to the thirty-fourth embodiment has the same system configuration as that of the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

This DC voltage / active power control circuit inputs the output of the DC voltage control circuit 151 of the first stage and the output of the DC voltage control circuit 152 of the second stage to the minimum value selection circuit 24 and outputs the smaller value. The output is selected and output, and the output of the minimum value selection circuit 24 and the output of the DC voltage control circuit 153 of the third stage are input to the maximum value selection circuit 25 to select and output the larger value. The other structure is the same as that of the control circuit of the thirty-second embodiment.

In the control device of the AC / DC converter configured as described above, the dead range of the dead zone circuit 18 is ± ΔPref, the value of the DC voltage set value EdpH is Edp + ΔEdp, and the value of the DC voltage set value EdpL is Edp-ΔEdp. When set, characteristics of DC voltage and active power as shown in FIG. 31 are obtained. That is, when the operating value of active power is within the range of ± ΔPref with respect to the active power set value Pref, the DC voltage is controlled to be constant according to the set value Edp, and it is effective when the operating value of active power is out of the range of Pref ± ΔPref. The DC voltage set value Edp is corrected according to the magnitude of the detected power value, and the characteristic becomes a downward-sloping or upward-sloping characteristic. When the DC voltage exceeds the range of Edp ± ΔEdp,
The constant DC voltage is controlled so that the DC voltage becomes Edp + ΔEdp or Edp−ΔEdp.

According to such an embodiment also, the 32nd
It is possible to obtain the same effects as those of the embodiment described above.

(35th Embodiment) FIG. 44 shows the 35th embodiment.
FIG. 3 is a control block diagram showing a partial configuration of the DC power transmission system according to the embodiment of the present invention and showing an internal configuration of a DC voltage / active power control circuit in a control device for an AC / DC exchanger.

The multi-terminal DC power transmission system according to the thirty-fifth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

In this DC voltage / active power control circuit, the difference between the set value Pref of the active power and the detection value Pa is calculated by the amplifiers 191, 19 having the respective amplification factors r1, r2, r3.
Give to 2, 193. The output of the amplifier 191 is added to the DC voltage setting value Edp to obtain the corrected DC voltage setting value Edp '. Further, the output of the amplifier 192 is added to the upper limit value Edmax for the DC voltage set value to obtain a corrected upper limit value Edmax ', and the output of the amplifier 193 is added to the lower limit value Edmin for the DC voltage set value to be corrected lower limit value Edmin. Get ′. Corrected upper limit value Edmax 'and corrected lower limit value Edmin'
Are used as upper and lower limit values of the limiter circuit 27. On the other hand, the corrected DC voltage set value Edp 'is input to the limiter circuit 27 and Edmax' which is the upper and lower limit value.
To Edmin '. Limiter circuit 27
The limited DC voltage set value Edp ″, which is the output of the DC voltage, is compared with the detected DC voltage value Ed and is applied to the DC voltage control circuit 15 composed of, for example, a proportional integration circuit. Control is performed so that the detected value Ed becomes equal to the limited DC voltage set value Edp ″.

Here, the amplification factor r2 of the amplifier 192 and the amplification factor r3 of the amplifier 193 are set to values smaller than the amplification factor r1 of the amplifier 191. The upper limit Edmax for the DC voltage set value is set to a value larger than the set value Edp, and the lower limit Edmin to the DC voltage set value is set to a value smaller than the set value Edp.

In the control apparatus for an AC / DC converter configured as described above, the DC voltage set value Edp is corrected by the value obtained by multiplying the difference between the set value Pref of the active power and the detected value Pa by the proportional constant r1, and the limiter circuit is corrected. 27 is input. Further, the upper limit value Emax for the DC voltage set value is corrected by a value obtained by multiplying the difference between the set value Pref of active power and the detected value Pa by the proportional constant r2, and the constant of proportionality is added to the difference between the set value Pref of active power and the detected value Pa. The lower limit E to the DC voltage set value multiplied by r3
min is corrected. The corrected upper limit value and the corrected lower limit value are given to the limiter circuit 27, and the corrected DC voltage setting value is restricted so as not to deviate from the range of the corrected upper limit value and the corrected lower limit value. . The DC voltage control circuit 15 controls the DC voltage control circuit 15 so that the limited DC voltage set value becomes equal to the DC voltage detection value.

Using the control circuit of FIG. 44 which operates in this manner, the characteristics of DC voltage and active power as shown in FIG. 45 are obtained. That is, when the operating value of the active power is equal to the active power setting value Pref, the DC voltage setting value Edp and its upper limit value Edmax and lower limit value Edmin are not corrected, and Edp is smaller than the upper limit value Edmax and the lower limit value. Value Edm
Since the value is larger than in, the final set value Edp ″ of the DC voltage is equal to the initial set value Edp. Therefore, the DC voltage is controlled to the value as the set value Edp initially given, and the operating value of active power and effective If there is a difference in the power setting value Pref,
The DC voltage set value Edp and its upper limit value Edmax and lower limit value Edmin are respectively corrected according to the magnitude of the difference.
The corrected DC voltage set value Edp 'is point 2 in FIG.
And the corrected upper limit value Edmax 'are the values on the line connecting the points 1 and 2 and the corrected lower limit value Edmi' on the line connecting the points 1 and 2.
n'is a value on the line connecting points 3 and 4.

Since Edmax 'is used as the upper limit value for the set value Edp' and Edmin 'is used as the lower limit value for the set value Edp', the relationship between the finally obtained DC voltage and the active power is point 1 The characteristic is a combination of 2, 3, and 4. As a result, when the operating value of the DC voltage is close to the set value Edp, control is performed so that the active power is kept close to the set value Pref by reducing the rate of change of the active power with respect to the change of the DC voltage. It will be. When the operating value of the DC voltage fluctuates significantly from the set value Edp, control is performed so that the DC voltage does not deviate further from the set value by reducing the rate of change of the DC voltage with respect to the change of active power. Be seen.

According to such an embodiment, since the DC power transmission system is constituted by the converter having the control circuit shown in FIG. 44, the active power and the DC voltage are normally controlled so as to be equal to the set values. be able to. Furthermore, if the active power of the entire DC transmission system becomes unbalanced,
If the operating value of the DC voltage is close to the DC voltage setting value,
The active power is controlled to be kept close to the set value by reducing the ratio of the change in the active power to the change in the DC voltage, and when the operating value of the DC voltage greatly deviates from the set value of the DC voltage, By reducing the ratio of the change of the DC voltage to the change of the active power, it is possible to perform the operation while suppressing the further change of the DC voltage.

(Thirty-sixth Embodiment) The thirty-sixth embodiment is an example in which the limiter circuit is used in the thirty-fifth embodiment, instead of the minimum value selection circuit and the maximum value selection circuit. is there.

FIG. 46 shows a partial configuration of a DC power transmission system according to the 36th embodiment, and is a control block diagram showing an internal configuration of a DC voltage / active power control circuit in a control device for an AC / DC exchanger. Is.

The multi-terminal DC power transmission system according to the thirty-sixth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

This DC voltage / active power control circuit uses the difference between the set value Pref of the active power and the detected value Pa as the amplifiers 191 and 19 having respective amplification factors r1, r2 and r3.
2, 193, and the output of the amplifier 191 is added to the DC voltage setting value Edp to obtain a corrected DC voltage setting value Edp '. Further, the output of the amplifier 192 is added to the upper limit value Edmax for the DC voltage set value to obtain a corrected upper limit value Edmax ', and the output of the amplifier 193 is added to the lower limit value Edmin for the DC voltage set value to be corrected lower limit value Edmin. Get ′. Corrected DC voltage set value Edp 'and corrected lower limit value Edmin'
Is given to the maximum selection circuit 25 and the larger value is selected. Further, the output of the maximum selection circuit 25 and the corrected upper limit value Edmax 'are given to the minimum selection circuit 24, and the smaller value is selected. The DC voltage control circuit 15 performs control so that the DC voltage detection value Ed becomes equal to the output of the minimum selection circuit 24. Here, the amplification factor r2 of the amplifier 192 and the amplification factor r3 of the amplifier 193 are the amplification factor r of the amplifier 191.
Set a value smaller than 1. The upper limit Edmax for the DC voltage set value is larger than the DC voltage set value Edp, and the lower limit Edmin for the DC voltage set value is the DC voltage set value E
Set a value smaller than dp.

In the control apparatus for the AC / DC converter configured as described above, the characteristics of DC voltage and active power shown in FIG. 45 are obtained, and the finally obtained relationship between DC voltage and active power is as follows.
The characteristics are obtained by connecting points 1, 2, 3, and 4. As a result, when the operating value of the DC voltage is close to the set value Edp, the active power is controlled to be kept close to the set value by reducing the rate of change of the active power with respect to the change of the DC voltage. When the operating value of the DC voltage greatly changes from the set value Edp, the ratio of the change of the DC voltage with respect to the change of the active power is reduced so that the DC voltage is controlled so as not to deviate further from the set value.

According to such an embodiment also, the 35th
It is possible to obtain the same effects as those of the embodiment described above.

(Thirty-Seventh Embodiment) FIG. 47 shows a thirty-seventh embodiment.
FIG. 3 is a control block diagram showing a partial configuration of the DC power transmission system according to the embodiment of the present invention and showing an internal configuration of a DC voltage / active power control circuit in a control device for an AC / DC exchanger.

The multi-terminal DC power transmission system according to the thirty-seventh embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

This DC voltage / active power control circuit is provided with DC voltage set values Edp, EdpH, and EdpL having three different values. EdpH is set to a value larger than Edp and EdpL is set to a value smaller than Edp. Active power setting value Pref and detection value P
The difference of a is given to the amplifiers 191, 192, 193 having the respective amplification factors r1, r2, r3. Amplifier 1
The output of 91 is added to the DC voltage setting value Edp to obtain the corrected DC voltage setting value Edp '. In addition, the output of the amplifier 192 is added to the DC voltage set value EdpH to correct the set value Edp.
H ′ is obtained and the output of the amplifier 193 is set to the DC voltage set value EdpL
To obtain a corrected set value EdpL '.

The direct-current voltage control circuit 151 of the first stage controls so that the detected direct-current voltage value Ed becomes equal to the corrected direct-current voltage set value Edp ', and the direct-current voltage control circuit 15 of the second stage is controlled.
In 2, the DC voltage set value E corrected by the DC voltage detection value Ed
The DC voltage control circuit 153 in the third stage controls the DC voltage detection value Ed to be equal to the corrected DC voltage set value EdpL '.

The output of the first-stage DC voltage control circuit 151 is used as an upper limit value for the output of the second-stage DC voltage control circuit 152, and is used as the second-stage DC voltage control circuit 1
The output of 52 is used as a lower limit value for the output of the third-stage DC voltage control circuit 153, and the output of the third-stage DC voltage control circuit 153 is given to the AC current control circuit 10 as the final output Idref.

Here, the amplification factor r2 of the amplifier 192 and the amplification factor r3 of the amplifier 193 are the amplification factor r1 of the amplifier 191.
Set a smaller value. The first-stage DC voltage control circuit 151, the second-stage DC voltage control circuit 152, and the third-stage DC voltage control circuit 153 are control circuits each composed of, for example, a proportional-integral circuit. As the output limit values other than the above-mentioned upper limit value or lower limit value, a fixed value determined from the rated capacity of the converter is set.

With the control device for the AC / DC converter configured as described above, the characteristics of DC voltage and active power as shown in FIG. 45 can be obtained. That is, when the operating value of the active power is equal to the active power setting value Pref, the DC voltage setting values Edp, E
Since no correction is made to dpH and EdpL, the output of the second-stage DC voltage control circuit 152 is in the upper limit limiter state, and the third-stage DC voltage control circuit is in the lower limit limiter state. , The DC voltage is controlled to be equal to the set value Edp.

Active power operating value Pa and active power set value P
When there is a difference in ref, the DC voltage set values Edp, EdpH, and EdpL are respectively corrected according to the magnitude of the difference.
The corrected DC voltage set value Edp 'is point 2 in FIG.
Is the value on the line connecting point 3 and the corrected set value EdpH 'is the value on the line connecting point 1 and point 2 and the corrected set value Edp
L'is a value on the line connecting points 3 and 4, and the relationship between the finally obtained DC voltage and active power is points 1, 2, 3, 4
It becomes the characteristic that tied.

Accordingly, when the operating value of the DC voltage is close to the set value, control is performed so that the active power is kept close to the set value by reducing the rate of change of the active power with respect to the change of the DC voltage. When the operating value of the DC voltage deviates from the set value, the ratio of the change of the DC voltage to the change of the active power is reduced so that the DC voltage is controlled so as not to deviate from the set value further.

According to such an embodiment, since the DC power transmission system is configured by the converter having the control circuit shown in FIG. 47, the active power and the DC voltage are normally set according to the set values. If the active power of the entire DC transmission system becomes unbalanced when the control is performed and the operating value of the DC voltage is within a certain range, the ratio of the change of the active power to the change of the DC voltage is By controlling so that the active power is kept close to the set value, and when the operating value of the DC voltage deviates from a certain range, the ratio of the change of the DC voltage to the change of the active power is decreased. By doing so, the operation can be performed while suppressing further fluctuations in the DC voltage.

(38th Embodiment) In the 38th embodiment, the upper and lower limits of the output of the first-stage DC voltage control circuit and the output of the first-stage DC voltage control circuit in the 37th embodiment are applied. This is an example in which what is used as a value is replaced with a combination of a minimum value selection circuit and a maximum value selection circuit.

The multi-terminal DC power transmission system according to the thirty-eighth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 48 shows the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC converter provided in the DC power transmission system according to the 38th embodiment.

This DC voltage / active power control circuit gives the output of the first-stage DC voltage control circuit 151 and the output of the second-stage DC voltage control circuit 152 to the minimum value selection circuit 24 and selects the smaller value. Then, the output of the minimum value selection circuit 24 and the output of the DC voltage control circuit 153 of the third stage are set to the maximum value selection circuit 25.
The larger value is selected and output. Other configurations are the same as those of the control circuit of the thirty-seventh embodiment.

In the control device for an AC / DC converter configured as described above, the characteristics of DC voltage and active power as shown in FIG. 45 can be obtained as in the thirty-seventh embodiment. That is,
When the operating value of the active power is equal to the active power setting value Pref, the DC voltage setting values Edp, EdpH, EdpL are not corrected, and the output of the first-stage DC voltage control circuit 151 is the second-stage DC voltage. Since it is smaller than the output of the voltage control circuit 152 and larger than the output of the third-stage DC voltage control circuit,
The DC voltage is controlled to be equal to the set value Edp.

Active power operation value Pa and active power set value P
When there is a difference in ref, the DC voltage setting values Edp, EdpH, EdpL are respectively corrected according to the magnitude of the difference, and the corrected DC voltage setting value Edp 'connects points 2 and 3 in FIG. The value on the elliptic line, the corrected set value EdpH 'is the value on the line connecting point 1 and point 2, and the corrected set value EdpL'
Is the value on the line connecting points 3 and 4, and the relationship between the finally obtained DC voltage and active power is the characteristic of connecting points 1, 2, 3, and 4.

Accordingly, when the operating value of the DC voltage is close to the set value, control is performed so that the active power is kept close to the set value by reducing the ratio of the change of the active power to the change of the DC voltage. When the operating value of the DC voltage deviates from the set value, the ratio of the change of the DC voltage to the change of the active power is reduced so that the DC voltage is controlled so as not to deviate from the set value further.

According to such an embodiment also, the 37th
It is possible to obtain the same effects as those of the embodiment described above.

(39th Embodiment) In the 39th embodiment, the set value is corrected before the difference between the DC voltage set value and the detected value is calculated in the 37th embodiment. In this example, the difference between the DC voltage set value and the detected value is calculated and then corrected.

The multi-terminal DC power transmission system according to the thirty-ninth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 49 shows the internal structure of the DC voltage / active power control circuit in the control device for the AC / DC converter provided in the DC power transmission system according to the 39th embodiment.

This DC voltage / active power control circuit adds the output of the amplifier 191 to the difference ΔEd between the DC voltage set value Edp and the detected value Ed to make a correction, and detects the output of the amplifier 192 as the DC voltage set value EdpH. Correction is performed by adding to the difference ΔEdH of the value Ed, and the output of the amplifier 193 is added to the difference ΔEdL between the DC voltage setting value EdpL and the detected value Ed to perform correction. The DC voltage control circuits 151, 152 and 153 respectively correct the correction. Differences in the DC voltage generated ΔEd ′, ΔEdH ′, Δ
The configuration is such that control is performed so that EdL 'becomes zero. The other structure is the same as that of the control circuit according to the thirty-seventh embodiment shown in FIG.

In the control apparatus for the AC / DC converter configured as described above, the same DC voltage and active power characteristics as those of the thirty-seventh embodiment as shown in FIG. 45 can be obtained. That is, when the operating value of active power is equal to the active power setting value Pref, the DC voltage differences ΔEd, ΔEdH, and ΔEdL are not corrected, and the output of the second-stage DC voltage control circuit 152 reaches the upper limit. In the applied state, the output of the third-stage DC voltage control circuit 153 is in the lower limit state, so that the DC voltage is controlled to be equal to the set value Edp.

Active power operating value and active power set value Pref
If there is a difference between the DC voltage and the active power, the difference between the DC voltage differences ΔEd, ΔEdH, and ΔEdL are corrected according to the magnitude of the difference.
The characteristic is a combination of 2, 3, and 4.

As a result, when the operating value of the DC voltage is close to the set value, control is performed so that the active power is kept close to the set value by reducing the change of the active power with respect to the change of the DC voltage. When the operating value of the voltage deviates from the set value, the change in the DC voltage with respect to the change in the active power is reduced so that the DC voltage does not deviate further from the set value.

Also according to such an embodiment, FIG.
By configuring a DC power transmission system with a converter equipped with the control circuit shown in Fig. 1, normally the active power and DC voltage are controlled so that they are as set, and the active power of the entire DC power transmission system is unbalanced. In this case, if the operating value of the DC voltage is within a certain range, the active power is kept close to the set value by reducing the ratio of the change of the active power to the change of the DC voltage. Control
When the operating value of the DC voltage deviates from a certain range, the operation can be performed while suppressing the further fluctuation of the DC voltage by reducing the ratio of the change of the DC voltage to the change of the active power. it can.

40th Embodiment FIG. 50 shows a 40th embodiment.
FIG. 3 is a control block diagram showing a partial configuration of the DC power transmission system according to the embodiment of the present invention and showing an internal configuration of a DC voltage / active power control circuit in a control device for an AC / DC exchanger.

Since the multi-terminal DC power transmission system according to the fortieth embodiment has the same system configuration as that of the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

This DC voltage / active power control circuit inputs the difference between the set value Pref of the active power and the detected value Pa to the dead zone circuit 18 having a preset dead range, and amplifies the output of the dead zone circuit 18 to a certain level. It is input to the amplifier 191 having the rate r1. On the other hand, the difference between the set value Pref of the active power and the detected value Pa is input to the amplifier 192 having a constant amplification factor r2. Then, the outputs of both amplifiers 191 and 192 are added, and the added value is further added to the DC voltage setting value Edp to obtain the corrected DC voltage setting value Edp '. The DC voltage control circuit 15 controls so that the detected DC voltage value Ed becomes equal to the corrected DC voltage set value Edp ', and the output of the DC voltage control circuit 15 is finally set as the output Iref.

In the control device for the AC / DC converter configured as described above, when the dead range of the dead zone circuit 18 is ± ΔPref, the characteristics of DC voltage and active power as shown in FIG. 51 are obtained. That is, when the operating value of the active power is equal to the active power setting value Pref, the dead zone circuit 18, the amplifier 19
1 and the outputs of the amplifier 192 become zero, the DC voltage setting value Edp is not corrected, and the DC voltage is controlled according to the initially set value Edp.

When there is a difference between the operating value of active power and the set value Pref, if the magnitude of the difference is within the range of ± ΔPref, the dead zone circuit 18 and the output of the amplifier 191 become zero, but the amplifier 192 Output is a value proportional to the difference between the set value Pref of the active power and the detected value Pa, the DC voltage set value Edp is corrected according to the magnitude of the difference, and the corrected DC voltage set value Edp ′ is It is a value on the line connecting points 2 and 3 in FIG.

Also, the operating value of active power and active power set value
When the difference in ref becomes large and exceeds the dead range ± ΔP ref, the dead band circuit 18 and the output of the amplifier 191 are output from the amplifier 19.
The value of the same sign as the output of 2 is added to the output of the amplifier 192, and the DC voltage set value Edp is corrected by that value. Therefore, the ratio of the change of the DC voltage to the change of the operating value of the active power becomes large, and the corrected DC voltage set value Edp 'is on the line connecting point 1 and point 2 and point 3 and point 4 in FIG. It becomes a value. The relationship between the finally obtained DC voltage and the active power has a characteristic in which points 1, 2, 3, and 4 are connected. As a result, when the operating value of active power is close to the set value, control is performed so that the active power is kept close to the set value by reducing the ratio of the change in DC voltage to the change in active power. When the operating value of is deviated from the set value, the ratio of the change of the active power with respect to the change of the DC voltage is reduced, so that the active power is controlled so as not to deviate from the set value.

According to such an embodiment, the converter having the control circuit shown in FIG. 50 constitutes the DC power transmission system, so that the active power and the DC voltage are normally controlled so as to be equal to the set values. Furthermore, when the active power of the entire DC transmission system becomes unbalanced, if the operating value of the DC voltage is within a certain range, the rate of change of the active power with respect to the change of the DC voltage is reduced. By doing so, the active power is controlled to be kept close to the set value, and when the operating value of the DC voltage deviates from a certain range, the ratio of the change of the DC voltage to the change of the active power is reduced. The operation can be performed while suppressing the DC voltage from changing further.

(Forty-First Embodiment) In the forty-first embodiment, the direct current voltage setting value is corrected and then is compared with the detected direct current voltage value in the forty-first embodiment. This is an example in which before the voltage setting value is corrected, the detected value is compared with the DC voltage detection value and the difference is corrected.

FIG. 52 shows a partial configuration of a DC power transmission system according to the forty-first embodiment, and is a control block diagram showing an internal configuration of a DC voltage / active power control circuit in a control device for an AC / DC exchanger. Is.

Since the multi-terminal DC power transmission system according to the forty-first embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

This DC voltage / active power control circuit inputs the difference between the set value Pref of the active power and the detected value Pa to the dead zone circuit 18 having a preset dead range, and amplifies the output of the dead zone circuit 18 to a certain level. It is input to the amplifier 191 having the rate r1. Further, the difference between the set value Pref of the active power and the detection value Pa is input to the amplifier 192 having a constant amplification factor r2. Then, the value obtained by adding the outputs of the amplifiers 191 and 192 is further added to the difference ΔEd between the DC voltage setting value Edp and the DC voltage detection value Ed to obtain the corrected DC voltage difference ΔE.
Get d '. The DC voltage control circuit 15 performs control so that the corrected DC voltage difference ΔEd ′ becomes zero.

In the controller of the AC / DC converter configured as described above, when the dead zone of the dead zone circuit 18 is ± ΔPref, the same DC voltage and active power characteristics as shown in FIG. 51 are obtained. As a result, when the operating value of the active power is close to the set value, the ratio of the change of the DC voltage to the change of the active power is reduced so that the DC voltage is controlled to be close to the set value. When the operating value of is deviated from the set value, the ratio of the change of the active power with respect to the change of the DC voltage is reduced, so that the active power is controlled so as not to deviate from the set value.

According to such an embodiment, the 40th
It is possible to obtain the same effects as those of the embodiment described above.

(Twenty-second Embodiment) FIG. 53 shows a forty-second embodiment.
FIG. 3 is a control block diagram showing a partial configuration of the DC power transmission system according to the embodiment of the present invention and showing an internal configuration of a DC voltage / active power control circuit in a control device for an AC / DC exchanger.

Since the multi-terminal DC power transmission system according to the forty-second embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

The DC voltage / active power control circuit detects the difference between the DC voltage set value Edp and the detected value Ed by the dead band circuit 22.
To the amplifier 20 having a constant amplification factor K2
Enter 2 The output of the dead band circuit 22 is set to a constant amplification factor K.
The output is added to the output of the amplifier 202 having a constant amplification factor K2 via the amplifier 201 having 1 and this added value is further added to the active power setting value Pref to obtain a corrected active power setting value Pref '. The active power control circuit 16 controls the active power detection value Pa to be equal to the corrected active power setting value Pref ', and the output of the active power control circuit 16 is given to the alternating current circuit 10 as the final output Idref. .

In the control device for an AC / DC converter configured as described above, when the dead range of the dead zone circuit 22 is ± ΔEdp, the characteristics of DC voltage and active power as shown in FIG. 54 are obtained. That is, when the operating value of the DC voltage is equal to the set value Edp, the dead zone circuit 22, the amplifier 201, the amplifier 2
Since the output of 02 is zero, the active power setting value P
The ref power is not corrected, and the active power is controlled to the value set according to the initial set value Pref.

When there is a difference between the operating value of the DC voltage and the set value Edp, if the difference is within the range of ± ΔEdp,
The outputs of the dead zone circuit 22 and the amplifier 201 are zero, but the outputs of the amplifier 202 are the set value Edp and the detected value Ed of the DC voltage.
Since the value is proportional to the difference between the two, the active power setting value Pref is corrected according to the difference, and the corrected active power setting value Pref
ref 'is a value on the line connecting points 2 and 3 in FIG.

When the difference between the operating value of the DC voltage and the set value Edp becomes large and exceeds the dead range ± ΔEdp, the outputs of the dead band circuit 22 and the amplifier 201 have the same sign as the output of the amplifier 202, and the amplifier 202 Is added to the output of the above-mentioned value, and the active power set value Pref is corrected by that value. Therefore, the ratio of the change in the active power to the change in the DC voltage becomes large, and the corrected active power set value Pref 'is shown in FIG.
It is a value on a line connecting points 1 and 2 and points 3 and 4 in. The relationship between the finally obtained DC voltage and the active power has a characteristic in which points 1, 2, 3, and 4 are connected. As a result, when the operating value of the DC voltage is close to the set value Edp, the active power is controlled to be kept close to the set value by reducing the ratio of the change of the active power to the change of the DC voltage. When the operating value of the DC voltage deviates from the set value Edp, the ratio of the change of the DC voltage with respect to the change of the active power is reduced so that the DC voltage is controlled so as not to deviate further from the set value.

According to such an embodiment, since the DC power transmission system is constituted by the converter having the control circuit shown in FIG. 53, the active power and the DC voltage are normally controlled so as to meet the set values. be able to. Furthermore, if the active power of the entire DC transmission system becomes unbalanced,
If the operating value of the DC voltage is close to the DC voltage setting value,
The active power is controlled to be kept close to the set value by reducing the ratio of the change in the active power to the change in the DC voltage, and when the operating value of the DC voltage greatly deviates from the set value of the DC voltage, By reducing the ratio of the change of the DC voltage to the change of the active power, it is possible to perform the operation while suppressing the further change of the DC voltage.

(Forty-Third Embodiment) In the forty-third embodiment, the difference between the active power set value and the detected value is corrected after the correction of the active power set value in the forty-second embodiment. In this example, the difference between the set value and the detected value is calculated and then corrected.

The multi-terminal DC power transmission system according to the forty-third embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 55 shows a partial configuration of a DC power transmission system according to the 43rd embodiment, and is a control block diagram showing an internal configuration of a DC voltage / active power control circuit in a control device for an AC / DC exchanger. Is.

This DC voltage / active power control circuit detects the difference between the DC voltage set value Edp and the detected value Ed by the dead band circuit 22.
And the amplifier 202 having a constant amplification factor K2, and the output of the dead band circuit 22 is inputted to the amplifier 2 having a constant amplification factor K1.
01 to the output of the amplifier 202 having the amplification factor K2, and the added value is further added to the active power setting value Pref.
Is added to the difference ΔP between the active power detection values Pa to obtain a corrected active power difference ΔP ′. The active power control circuit 16 performs control so that the corrected active power difference ΔP ′ becomes zero.

In the control device for the AC / DC converter configured as described above, the DC voltage and active power characteristics shown in FIG. 54 can be obtained when the dead range of the dead zone circuit 22 is ± ΔEdp. As a result, when the operating value of the DC voltage is close to the set value, control is performed so that the active power is kept close to the set value by reducing the ratio of the change of the active power to the change of the DC voltage. When the operating value of 1 deviates from the set value, the change of the DC voltage with respect to the change of the active power is reduced, so that the DC voltage is controlled so as not to deviate from the set value.

According to such an embodiment also, the 42nd
It is possible to obtain the same effects as those of the embodiment described above.

(Forty-fourth Embodiment) FIG. 56 shows a forty-fourth embodiment.
FIG. 3 is a control block diagram showing a partial configuration of the DC power transmission system according to the embodiment of the present invention and showing an internal configuration of a DC voltage / active power control circuit in a control device for an AC / DC exchanger.

The multi-terminal DC power transmission system according to the forty-fourth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

This DC voltage / active power control circuit is provided with DC voltage set values Edp, EdpH and EdpL having three different values, and the set value Edp is set smaller than EdpH and larger than EdpL. Active power detection value Pa and set value P
The difference of ref is input to the amplifier 19 having a constant amplification factor r, while the difference between the DC voltage setting value Edp and the detection value Ed is
Input to the dead zone circuit 22 having a preset dead zone. Then, the direct-current voltage control circuit 151 of the first stage controls so that the output of the dead zone circuit 22 and the output of the amplifier 19 become equal. In addition, the second stage DC voltage control circuit 15
In step 2, the DC voltage detection value Ed is controlled to be equal to the DC voltage setting value EdpH, and the DC voltage control circuit 1 of the third stage is controlled.
At 53, control is performed so that the DC voltage detection value Ed becomes equal to the DC voltage set value EdpL.

The output of the first stage DC voltage control circuit 151 is used as an upper limit value for the output of the second stage DC voltage control circuit 152, and the output of the second stage DC voltage control circuit 152 is the third stage. Is used as a lower limit value for the output of the DC voltage control circuit 153. The output of the DC voltage control circuit 153 of the third stage is given to the AC current control circuit 10 in FIG. 65 as the final output Idref.

The direct voltage control circuit 151 of the first stage,
The second-stage DC voltage control circuit 152 and the third-stage DC voltage control circuit 153 are control circuits configured by, for example, a proportional-integral circuit, and the above-described upper and lower limit values are the rated capacity of the converter. A fixed value determined from the above is set.

In the control apparatus for the AC / DC converter configured as described above, when the dead range of the dead zone circuit 22 is ± ΔEdp, the characteristics of DC voltage and active power as shown in FIG. 36 are obtained. That is, when the operating value of the DC voltage is within the range of Edp ± ΔEdp with respect to the set value Edp, the dead zone circuit 22
Output becomes zero, the first-stage DC voltage control circuit 15
1, the active power is controlled according to the set value Pref, and the DC voltage detection value Ed is smaller than the set value EdpH and larger than EdpL. Therefore, the DC voltage control circuit 152 of the second stage is in the upper limit limiter state. The DC voltage control circuit 153 of the stage is operated with the lower limiter applied.
Therefore, the output of the first-stage DC voltage control circuit 151 becomes the final output Idref, and the active power is controlled according to the set value Pref. The operating value of the DC voltage is the set value Edp,
When the range of ± ΔEdp is exceeded, a value proportional to the exceeded value becomes the output of the dead zone circuit 22, and the value is controlled to be equal to the output of the amplifier 19, so that the active power increases as the DC voltage decreases. It has a characteristic of falling to the right or rising to the left as the DC voltage rises. When the fluctuation of the DC voltage further increases, for example, becomes larger than the set value EdpH, the DC voltage control circuit 152 of the second stage
Is switched to the DC voltage control with EdpH being the set value from the state of applying the upper limiter, and the DC voltage is controlled to be constant. On the contrary, when the DC voltage becomes a value smaller than the set value EdpL, the DC voltage control circuit 153 in the third stage switches from the state in which the lower limit is applied to the DC voltage control with EdpL as the set value, and the DC voltage is controlled to be constant. To do.

According to such an embodiment, since the DC power transmission system is configured by the converter including the control circuit shown in FIG. 56, normally, the power exchange according to the given active power setting value is performed, and the DC power transmission is performed. If the operating value of the voltage exceeds a certain range, the operating point of the active power is corrected by the fluctuation of the DC voltage so that the active power does not largely deviate from the set value and the fluctuation of the DC voltage is suppressed. When the fluctuation of the DC voltage becomes large, the DC voltage constant control is performed to prevent the DC voltage from drastically lowering or rising to operate.

(Forty-fifth Embodiment) In the forty-fifth embodiment, the outputs of the first-stage and second-stage DC voltage control circuits in the forty-fourth embodiment are used as upper and lower limit values. On the other hand, this is an example in which the same function is provided by the combination of retreating the minimum value selection circuit and the maximum value selection circuit.

The multi-terminal DC transmission system according to the forty-fifth embodiment has the same system configuration as the DC transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 57 shows a partial configuration of a DC power transmission system according to the 45th embodiment, and is a control block diagram showing an internal configuration of a DC voltage / active power control circuit in a control device for an AC / DC exchanger. Is.

This DC voltage / active power control circuit inputs the output of the DC voltage control circuit 151 of the first stage and the output of the DC voltage control circuit 152 of the second stage to the minimum value selection circuit 24 and outputs the smaller value. The output of the minimum value selection circuit 24 and the output of the DC voltage control circuit 153 of the third stage are selected and the maximum value selection circuit 2 is selected.
The value is input to 5, and the larger value is selected and output. Others are the same as those in the 44th embodiment.

In the control device for the AC / DC converter configured as described above, the DC voltage and active power characteristics shown in FIG. 36 are obtained when the dead range of the dead zone circuit 22 is ± ΔEdp. That is, the operating value of the DC voltage is the set value Edp,
When it is within the range of ± ΔEdp, the active power is set value Pref
When the control is performed so that the value is the same as the above, and the operating value of the DC voltage exceeds the range of Edp ± ΔEdp, the active power increases to the right as the DC voltage decreases, or decreases to the left as the DC voltage increases. It becomes a rising characteristic. When the variation of the DC voltage further increases and becomes a value smaller than the set value EdpL or a value larger than the set value EdpH, the DC voltage control is performed with EdpL and EdpH as the set values, and the DC voltage is controlled to be constant.

According to such an embodiment, the same effects as those of the 44th embodiment can be obtained.

(46th Embodiment) FIG. 58 shows the 46th embodiment.
FIG. 3 is a control block diagram showing a partial configuration of the DC power transmission system according to the embodiment of the present invention and showing an internal configuration of a DC voltage / active power control circuit in a control device for an AC / DC exchanger.

The multi-terminal DC transmission system according to the forty-sixth embodiment has the same system configuration as the DC transmission system shown in FIG.
The active power control circuit will be described in detail.

This DC voltage / active power control circuit uses the multiplier 2 for the difference ΔP between the set value Pref of the active power and the detection value Pa.
8 and calculates ΔP × ΔP, and the amplification factor r of the output
The corrected DC voltage set value Edp 'is obtained by adding to the DC voltage set value Edp through the amplifier 19 having The DC voltage control circuit 15 controls the DC voltage detection value Ed to be equal to the corrected DC voltage set value Edp '. The DC voltage control circuit 15 is, for example, a control circuit composed of a proportional-integral circuit, and its output is limited by upper and lower limit values determined by the rated capacity of the converter.

In the control device for the AC / DC converter configured as described above, the characteristics of DC voltage and active power as shown in FIG. 59 can be obtained. That is, the operating value of active power is the set value P
When it is equal to ref, the output of the amplifier 19 becomes zero.
The DC voltage setting value Edp is not corrected, and the DC voltage is controlled according to the initially set setting value Edp.

When there is a difference between the operating value of the active power and the set value Pref, a value proportional to the square of the difference is added to the DC voltage set value Edp, so that the DC voltage increases as the active power increases. The characteristic is a downward-sloping characteristic in which the DC voltage rises as the active power decreases.

When the difference between the set value of active power and the detected value is small, the value obtained by squaring the value becomes even smaller.
Although the DC voltage is corrected at a small rate, when the difference between the set value Pref of the active power and the detected value Pa becomes large, the value obtained by squaring the value changes at a larger rate, so the characteristic is as shown in FIG. It becomes a curve. As a result, when the operating value of the active power is close to the set value, control is performed so that the DC voltage is kept close to the set value by reducing the change in the DC voltage with respect to the change of the active power. When the value deviates from the set value, the change in the DC voltage with respect to the change in the active power is increased so that the active power does not deviate further from the set value.

According to this embodiment, the difference ΔP between the set value Pref of the active power and the detected value Pa is given to the multiplier 28 to calculate ΔP × ΔP, and the amplifier having the amplification factor r of its output. Since the corrected DC voltage set value Edp ′ is obtained by adding to the DC voltage set value Edp via 19,
Normally, control is performed so that the active power and the DC voltage are as set values, and when the active power of the entire DC transmission system becomes unbalanced, the DC voltage is prevented from largely deviating from the set value and effective. When the power operation value largely deviates from the set value, the operation can be performed while preventing the active power from further deviating from the set value.

(Forty-seventh Embodiment) In the forty-seventh embodiment, the multiplier shown in FIG. 59 is used in the forty-sixth embodiment, whereas the square root arithmetic circuit is used. This is an example in which desired characteristics are realized.

The multi-terminal DC transmission system according to the forty-seventh embodiment has the same system configuration as the DC transmission system shown in FIG.
The active power control circuit will be described in detail.

FIG. 60 is a control block diagram showing a part of the structure of the DC power transmission system according to the forty-seventh embodiment and showing the internal structure of the DC voltage / active power control circuit in the controller of the AC / DC exchanger. is there.

This DC voltage / active power control circuit inputs the difference between the set value Pref of the active power and the detected value Pa to the square root calculation circuit 29 to calculate the square root of the difference, and outputs the output to the DC voltage set value Edp. DC voltage set value E corrected by addition
Get dp '. The DC voltage control circuit 15 controls the DC voltage detection value Ed to be equal to the corrected DC voltage set value Edp '.

The square root operation circuit 29 outputs y = r.multidot. (X) if the input x is a positive value as shown in FIG.
^1/2 , output y = -r (-x) if input x is negative
It is a digital circuit that incorporates a table of output y for input x with a relation of ^1/2 . In the control apparatus for an AC / DC converter configured as described above, when the control circuit of FIG. 60 is used, the characteristics of DC voltage and active power as shown in FIG. 62 are obtained. That is, the operating value of active power is the set value Pre
When it is equal to f, the output of the amplifier 19 becomes zero, so that the DC voltage setting value Edp is not corrected and the DC voltage is controlled according to the initially set setting value Edp.

When there is a difference between the operating value of the active power and the set value Pref, a value proportional to the square root of the difference is added to the DC voltage set value Edp, so that the DC voltage increases as the active power increases. The characteristic is a downward-sloping characteristic in which the DC voltage rises as the active power decreases.

When the difference between the set value of active power and the detected value is small, the rate of change in the square root value is larger than when the difference between the set value of active power and the detected value is large. The curve is as indicated by 62. As a result, when the operating value of active power is close to the set value, control is performed so that the active power is kept close to the set value by increasing the change in DC voltage with respect to the change in active power. When the value deviates from the set value, the change in the DC voltage with respect to the change in the active power is reduced so that the DC voltage does not largely deviate from the set value.

According to such an embodiment, by using the control circuit shown in FIG. 60, the active power and the DC voltage are normally controlled so as to be set values, and the active power of the entire DC power transmission system is controlled. If the DC voltage becomes unbalanced, the active power is prevented from largely deviating from the set value, and if the DC voltage operating value greatly deviates from the set value, the DC voltage further deviates from the set value. Driving can be performed while preventing

(Forty-Eighth Embodiment) FIG. 63 shows a forty-eighth embodiment.
FIG. 3 is a control block diagram showing a partial configuration of the DC power transmission system according to the embodiment of the present invention and showing an internal configuration of a DC voltage / active power control circuit in a control device for an AC / DC exchanger.

The multi-terminal DC power transmission system according to the forty-eighth embodiment has the same system configuration as the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

This DC voltage / active power control circuit multiplies the difference ΔEd between the set value Edp of the DC voltage and the detected value Ed by the multiplier 2
8 and calculates ΔEd × ΔEd, and outputs the output through the amplifier 20 having a constant amplification factor K to the active power setting value P.
It is added to ref to obtain a corrected active power setting value Pref '. The active power control circuit 16 controls the active power detection value Pa to be equal to the corrected active power set value Pref '.

In the control device for the AC / DC converter configured as described above, the characteristics of DC voltage and active power as shown in FIG. 62 are obtained. That is, when the detected value Ed of the DC voltage is equal to the set value Edp, the output of the amplifier 20 becomes zero, so the active power set value Pref is not corrected, and the active power is initially set to the set value Pref. Controlled as per. When there is a difference between the detected value Ed of the DC voltage and the set value Edp, a value proportional to the square of the difference is added to the active power set value Pref, so that the active power decreases as the DC voltage increases. However, the active power increases as the DC voltage decreases, and the characteristic is a downward slope. When the difference between the set value of the DC voltage and the detected value is small, the value obtained by squaring the value is even smaller, so the proportion of active power correction is small, but the difference between the set value of the DC voltage and the detected value is small. When it gets bigger,
Since the value obtained by squaring the value changes at a larger rate, the characteristic becomes a curve as shown in FIG. As a result, when the operating value of the DC voltage is close to the set value, control is performed so that the active power is kept close to the set value by reducing the change of the active power with respect to the change of the DC voltage. When the value deviates from the set value, the change in the active power with respect to the change in the DC voltage is increased to control so that the DC voltage does not deviate further from the set value.

According to such an embodiment, normally, the active power and the DC voltage are controlled so as to be as set values, and when the active power of the entire DC transmission system becomes unbalanced, the active power is When the DC voltage operation value largely deviates from the set value, the operation can be performed while preventing the DC voltage from further deviating from the set value.

(Forty-ninth Embodiment) FIG.
FIG. 3 is a control block diagram showing a partial configuration of the DC power transmission system according to the embodiment of the present invention and showing an internal configuration of a DC voltage / active power control circuit in a control device for an AC / DC exchanger.

The multi-terminal DC power transmission system according to the forty-ninth embodiment has the same system configuration as that of the DC power transmission system shown in FIG.
The active power control circuit will be described in detail.

This DC voltage / active power control circuit inputs the difference between the set value Edp of the DC voltage and the detected DC voltage value Ed into the square root calculation circuit 29 to calculate the square root of the difference, and outputs the output to the active power set value. A corrected active power set value Pref 'is obtained by adding to Pref. The active power control circuit 16 controls the active power detection value Pa to be equal to the corrected active power set value Pref '. Here, the square root calculation circuit 29
61, for example, as shown in FIG. 61, if the input x is a positive value, the output y = r√x, and if the input x is a negative value, the output y is
It is a digital circuit in which a table of an output y with respect to an input x having a relation of = -r · √-x is incorporated.

In the control device for the AC / DC converter configured as described above, the characteristics of the DC voltage and active power as shown in FIG. 59 are obtained, and when the detected value Ed of the DC voltage is equal to the set value Edp, Since the output of the amplifier 20 becomes zero, the active power set value Pref is not corrected, and the active power is controlled according to the initially set set value Pref. When there is a difference between the detected value Ed of the DC voltage and the set value Edp, a value proportional to the square root of the difference is added to the active power set value Pref, so that the active power decreases as the DC voltage increases. However, the active power increases as the DC voltage decreases, and the characteristic is a downward slope. When the difference between the set value of the DC voltage and the detected value is small, the rate of change in the square root value is larger than when the difference between the set value of the DC voltage and the detected value is large, so the characteristics are shown in FIG. It becomes a curve like this. As a result, when the operating value of the DC voltage is close to the set value, control is performed so that the DC voltage is kept close to the set value by increasing the change of the active power with respect to the change of the DC voltage. When the value deviates from the set value, the change in the active power with respect to the change in the DC voltage is reduced so that the active power does not largely deviate from the set value.

According to such an embodiment, by using the control circuit shown in FIG. 64, the active power and the DC voltage are normally controlled so as to be set values, and the active power of the entire DC power transmission system is controlled. If the DC voltage becomes unbalanced, the active power is prevented from largely deviating from the set value, and if the DC voltage operating value greatly deviates from the set value, the DC voltage further deviates from the set value. Driving can be performed while preventing

[0461]

According to the control device for an AC / DC converter of the present invention, the DC power transmission system composed of a plurality of converters operates while maintaining the active power and the DC voltage according to the given set values, and , Even if some of the converters are stopped due to an accident or the operating value of active power changes, control is performed by correcting the active power and DC voltage settings of a healthy converter. As a result, the operation can be performed while minimizing the fluctuations of the active power and the DC voltage of the healthy converter.

[Brief description of drawings]

FIG. 1 is a block diagram of a DC voltage / active power control circuit of a control device for an AC / DC converter according to a first embodiment.

FIG. 2 is a characteristic diagram illustrating a relationship between a DC voltage and active power according to the first embodiment.

FIG. 3 is a simulation waveform diagram comparing the operating characteristics of the first embodiment with a conventional control device.

FIG. 4 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a second embodiment.

FIG. 5 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a third embodiment.

FIG. 6 is a characteristic diagram illustrating a relationship between a DC voltage and active power according to the third embodiment.

FIG. 7 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a fourth embodiment.

FIG. 8 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a fifth embodiment.

FIG. 9 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a sixth embodiment.

FIG. 10 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a seventh embodiment.

FIG. 11 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to an eighth embodiment.

FIG. 12 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a ninth embodiment.

FIG. 13 is a characteristic diagram illustrating a relationship between a DC voltage and active power according to the ninth embodiment.

FIG. 14 is a simulation waveform diagram comparing operating characteristics when the control device for an AC / DC converter according to the ninth embodiment is applied and when the conventional control device is applied.

FIG. 15 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a tenth embodiment.

FIG. 16 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to an eleventh embodiment.

FIG. 17 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a twelfth embodiment.

FIG. 18 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a thirteenth embodiment.

FIG. 19 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a fourteenth embodiment.

FIG. 20 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a fifteenth embodiment.

FIG. 21 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a sixteenth embodiment.

FIG. 22 is a characteristic diagram illustrating the relationship between the DC voltage and active power in the sixteenth embodiment.

FIG. 23 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a seventeenth embodiment.

FIG. 24 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to an eighteenth embodiment.

FIG. 25 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a nineteenth embodiment.

FIG. 26 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a twentieth embodiment.

FIG. 27 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a twenty-first embodiment.

FIG. 28 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a twenty-second embodiment.

FIG. 29 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a 23rd embodiment.

FIG. 30 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a twenty-fourth embodiment.

FIG. 31 is a characteristic diagram illustrating the relationship between DC voltage and active power according to the twenty-fourth embodiment.

FIG. 32 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a twenty-fifth embodiment.

FIG. 33 is a characteristic diagram illustrating the relationship between DC voltage and active power according to the twenty-fifth embodiment.

FIG. 34 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a twenty-sixth embodiment.

FIG. 35 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a 27th embodiment.

FIG. 36 is a characteristic diagram for explaining the relationship between DC voltage and active power in the twenty-seventh embodiment.

FIG. 37 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a twenty-eighth embodiment.

FIG. 38 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a twenty ninth embodiment.

FIG. 39 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a thirtieth embodiment.

FIG. 40 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a thirty-first embodiment.

FIG. 41 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a 32nd embodiment.

FIG. 42 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a thirty-third embodiment.

FIG. 43 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a thirty-fourth embodiment.

FIG. 44 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a thirty-fifth embodiment.

FIG. 45 is a characteristic diagram illustrating the relationship between DC voltage and active power in the thirty-fifth embodiment.

FIG. 46 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a 36th embodiment.

FIG. 47 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a 37th embodiment.

FIG. 48 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a thirty-eighth embodiment.

FIG. 49 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a 39th embodiment.

FIG. 50 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a fortieth embodiment.

FIG. 51 is a characteristic diagram illustrating the relationship between DC voltage and active power in the fortieth embodiment.

FIG. 52 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a forty-first embodiment.

FIG. 53 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a forty-second embodiment.

FIG. 54 is a characteristic diagram illustrating the relationship between DC voltage and active power in the forty-second embodiment.

FIG. 55 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a forty-third embodiment.

FIG. 56 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a forty-fourth embodiment.

FIG. 57 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a 45th embodiment.

FIG. 58 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a forty-sixth embodiment.

FIG. 59 is a characteristic diagram illustrating the relationship between DC voltage and active power according to the 46th embodiment.

FIG. 60 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a 47th embodiment.

FIG. 61 is a diagram for explaining the characteristics of the input / output table incorporated in the square root calculation circuit, which is a part of the control device for the AC / DC converter according to the 47th embodiment;

FIG. 62 is a characteristic diagram illustrating the relationship between DC voltage and active power according to the 47th embodiment.

FIG. 63 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a forty-eighth embodiment.

FIG. 64 is a block diagram of a DC voltage / active power control circuit in a control device for an AC / DC converter according to a forty-ninth embodiment.

FIG. 65 is a configuration diagram of a main circuit and a control device of a DC power transmission system including a plurality of AC / DC converters.

FIG. 66 is a block diagram of a first conventional DC voltage / active power control circuit of a control device for an AC / DC converter applied to a two-terminal DC power transmission system.

FIG. 67 is a block diagram of a second conventional DC voltage / active power control circuit of a control device for an AC / DC converter applied to a multi-terminal DC transmission system.

FIG. 68 is a block diagram of a third conventional DC voltage / active power control circuit in the control device for the AC / DC converter applied to the multi-terminal DC power transmission system.

FIG. 69 is a characteristic diagram illustrating a relationship between a DC voltage and active power when a third conventional DC voltage / active power control circuit is applied.

[Explanation of symbols]

1, 1 '... AC bus bar 2, 2' ... Transformer for transformer 3, 3 '... Self-excited AC / DC converter 4 ... DC power converter 5 ... DC voltage detector 6 ... Active power detector 7 ... DC voltage / active power control Circuit 8 ... Reactive power detector 9 ... Reactive power control circuit 10 ... AC current control circuit 11 ... Three-phase / two-phase conversion circuit 12 ... PWM control circuit 13 ... Phase detection circuit 14 ... Pulse generation circuit 15 (151, 152, 153) ) ... DC voltage control circuit 16 ... Active power control circuit 17 ... Switch circuit 18 ... Dead band circuit 19 (191, 192, 193) ... Amplifier 20 (201, 202) ... Amplifier 21 (211, 21)
2) ... adder 22 ... dead zone circuit 23 (231, 23)
2) ... Adder 24 ... Minimum value selection circuit 25 ... Maximum value selection circuit 26 (261, 262) ... Adder 27 ... Limiter circuit 28 ... Multiplier 29 ... Square root calculation circuit Pref (Pref ') ... Active power set value Pa ... Active power detection value Edp (Edp ', Edp ", EdpH, EdpL) ... DC voltage setting value Ed ... DC voltage detection value r ... Amplification factor K ... Amplification factor .DELTA.Pref ... Active power insensitive range width .DELTA.Edp ... DC voltage insensitivity Range width or DC voltage set value bias ΔP (ΔP ′)… Difference between active power setting and detection value ΔEd (ΔEd ′, ΔEdH, ΔEdL)… Difference between DC voltage setting and detection value Pmax Output upper limit value Pmin ... Output lower limit value Edmax ... DC voltage upper limit value Edmin ... DC voltage lower limit value P1, P2 ... Active power dead range APR ... Active power control circuit AVR ... DC voltage control circuit LVG ... Minimum value selection Path HVG ... Maximum value selection circuit Idref ... AC current active power component setting value Iqref ... AC current reactive power component setting value Id ... AC current reactive power component detection value Iq ... AC current reactive power component detection value Qref ... Invalid Power setting value Qa ... Reactive power detection value Cm ... Control rate φ ... Phase angle

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Koji Sakamoto 4-1, Egasaki-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Tokyo Electric Power Co., Inc. Electric Power Technology Laboratory (72) Midori Otsuki, 1-Toshiba-cho, Fuchu, Tokyo Company Toshiba Fuchu Factory (72) Inventor Hideo Takeda 1-1-1, Shibaura, Minato-ku, Tokyo Inside Toshiba Head Office Co., Ltd. (72) Inventor Noriko Kawakami No. 1 Toshiba Town, Fuchu City, Tokyo Inside Toshiba Fuchu Factory

Claims (19)

[Claims] 1. A control device for an AC / DC converter in a DC power transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, and a set value and detection of active power that the converter accommodates. If the difference from the value or the active power detection value deviates from the preset range, the DC voltage set value is corrected by adding a value proportional to the deviated magnitude, and the corrected DC voltage set value and A control device for an AC / DC converter, which is controlled so that the detected DC voltage becomes equal. 2. A control device for an AC / DC converter in a DC power transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, and a difference between a set value of a DC voltage and a detected value is calculated. If the difference obtained by multiplying the difference by a proportional constant is controlled to be zero, and the difference between the set value and the detected value of active power of the converter or the detected active power deviates from the preset range. The control device for the AC / DC converter is characterized in that the deviated magnitude and the multiplied value are controlled to be equal to each other. 3. A controller of an AC / DC converter in a DC power transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, and the difference between the set value and the detected value of the DC voltage is When the value deviates from the preset range, the active power set value interchanged by the converter is corrected by adding a value proportional to the deviated magnitude, and the corrected active power set value and active power detection value A control device for an AC / DC converter, which controls so that and become equal. 4. A control device for an AC / DC converter in a DC power transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, and a set value and detection of active power accommodating the converter are detected. When the difference between the set value of DC voltage and the detected value deviates from the preset range, it is deviated if the difference between the value and the detected value is deviated. A control device for an AC-DC converter, wherein the control is performed so that the magnitude and the multiplication value are equal. 5. A controller for an AC / DC converter in a DC power transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, and a set value and detection of active power accommodating the converter are detected. A value proportional to the difference between the values is added to each of the two different types of DC voltage setting values to correct both of the two types of different DC voltage setting values. The DC voltage control circuit of the first stage which controls so that the larger one of the two types of DC voltage set values and the detected value of the DC voltage are equal to each other, and the two types of DC voltage set values corrected by the correction means. The second-stage DC voltage control circuit that controls so that the smaller one of them becomes equal to the detected value of DC voltage, and the active power that controls so that the set value and the detected value of active power interchanged by the converter become equal. control And an output of the active power control circuit is used as an upper limit value with respect to an output value of the first-stage DC voltage control circuit, and an output of the first-stage DC voltage control circuit is used as an upper limit value. It is used as a lower limit value for the output value of the voltage control circuit, and the output of the second-stage DC voltage control circuit is used as the final control output value for the DC voltage and active power. Control device. 6. In a control device for an AC / DC converter in a DC power transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, a set value and effective value of active power that the converter accommodates The DC voltage setting value is corrected by adding a value proportional to the difference between the detected electric power values, the corrected DC voltage setting value is restricted so as not to deviate from a certain range, and the restricted DC voltage setting value is set. A control device for an AC / DC converter, wherein the control is performed so that the value and the detected value of the DC voltage are equal. 7. A control device for an AC / DC converter in a DC transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, and DC voltage set values of three different values are set. And this 3
Corrects the active power setting value by adding the value proportional to the difference between the intermediate DC voltage setting value and the DC voltage detection value among the DC voltage setting values of various types to the active power setting value that the converter can accommodate. Correction means, an active power control circuit for controlling the active power set value corrected by the correcting means to be equal to the active power detected value, and a DC voltage having the largest value among the three types of DC voltage set values. The first-stage DC voltage control circuit that controls so that the set value and the DC voltage detection value are equal, and the DC voltage set value that is the smallest of the three types of DC voltage set values and the DC voltage detected value are equal. And a second-stage DC voltage control circuit for performing the above control, wherein the output of the active power control circuit is used as an upper limit value for the output value of the first-stage DC voltage control circuit, and the first-stage DC voltage Control circuit Is used as the lower limit value for the output value of the second-stage DC voltage control circuit, and the output of the second-stage DC voltage control circuit is used as the final control output value for the DC voltage and active power. A control device for an AC / DC converter characterized in that. 8. A control device for an AC / DC converter in a DC transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, and three different DC voltage setting values are set. And this 3
Among the DC voltage setting values of the types, for the intermediate value setting value,
Correcting means for making a correction by adding a value proportional to the difference between the set value of the active power of the converter and the detected value, and the DC voltage set value corrected by this correcting means and the detected DC voltage are equal. A first-stage DC voltage control circuit for performing control, and a second-stage DC voltage control for performing control so that the DC voltage setting value having the largest value among the three types of DC voltage setting values becomes equal to the detected DC voltage value. A circuit, and a DC voltage control circuit of a third stage for performing control so that the DC voltage setting value of the smallest value among the three types of DC voltage setting values becomes equal to the DC voltage detection value, The output of the DC voltage control circuit is used as an upper limit value for the output value of the second stage DC voltage control circuit,
The output of the second-stage DC voltage control circuit is used as a lower limit value for the output value of the third-stage DC voltage control circuit,
A control device for an AC / DC converter, wherein the output of the DC voltage control circuit in the third stage is used as a final control output value for the DC voltage and active power. 9. A controller for an AC / DC converter in a DC power transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, and a setting value and detection of active power interchanged by the converter. When the difference value or the detected active power value deviates from the preset range, the DC voltage set value is corrected by adding a value proportional to the deviated magnitude, and the corrected DC voltage set value Is controlled so as not to deviate from a certain range, and the limited DC voltage setting value and the DC voltage detection value are controlled to be equal to each other. 10. A controller for an AC / DC converter in a DC power transmission system, wherein a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, and DC voltage set values of three different values are set. And the above 3
If the difference between the set value of the intermediate value and the detected value of the DC voltage among the DC voltage set values of the various types deviates from the preset range, the converter flexibility is added by adding a value proportional to the size of the deviation. Correction means for correcting the set value of active power, an active power control circuit for performing control so that the active power set value corrected by the correction means becomes equal to the active power detected value, and the three types of DC voltage set values The first-stage DC voltage control circuit that controls the DC voltage setting value of the largest value and the DC voltage detection value to be equal, and the DC voltage setting of the smallest value of the three types of DC voltage setting values A DC voltage control circuit in a second stage for performing control so that the detected value and the detected DC voltage are equal, and the output of the active power control circuit is used as an upper limit value for the output value of the DC voltage control circuit in the first stage. And before The output of the first-stage DC voltage control circuit is used as a lower limit value for the output value of the second-stage DC voltage control circuit, and the output of the second-stage DC voltage control circuit is used as the final value for the DC voltage and active power. A control device for an AC / DC converter, which is used as a general control output value. 11. A control device for an AC / DC converter in a DC power transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, among three DC voltage setting values having different values. The control value is controlled so that the multiplication value obtained by multiplying the difference between the intermediate value of the DC voltage setting value and the detected value of the DC voltage by the proportional constant becomes zero, and the setting value of the active power that the converter accommodates. And a detected value or an active power detected value deviates from a preset range, an active power control circuit that controls the deviated magnitude so that the value and the multiplication value are equal, and the three types of DC voltage settings. DC voltage control circuit of the first stage that controls so that the DC voltage setting value of the largest value and the DC voltage detection value become equal, and the DC value of the smallest value among the three types of DC voltage settings. Voltage setting value and DC voltage A second-stage DC voltage control circuit for controlling the output values to be equal, and using the output of the active power control circuit as an upper limit value to the output value of the first-stage DC voltage control circuit, The output of the DC voltage control circuit of the second stage is used as a lower limit value with respect to the output value of the DC voltage control circuit of the second stage, and the output of the DC voltage control circuit of the second stage is used as a final value for the DC voltage and active power. A control device for an AC / DC converter, which is used as a control output value. 12. A control device for an AC / DC converter in a DC power transmission system, wherein a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit. When the difference value or the detected active power value deviates from the preset range, a value proportional to the deviated magnitude is added to determine the intermediate value among the three different values of the DC voltage setting value. A correction unit that corrects the set value of the value, a first-stage DC voltage control circuit that performs control so that the DC voltage set value corrected by the correction unit and the DC voltage detection value become equal;
Control is performed so that the DC voltage setting value of the largest value among the DC voltage setting values of the types becomes equal to the DC voltage detection value 2
The DC voltage control circuit of the third stage and the DC voltage control circuit of the third stage which controls so that the DC voltage setting value of the smallest value among the three types of DC voltage setting values and the DC voltage detection value become equal. And using the output of the first-stage DC voltage control circuit as an upper limit value for the output value of the second-stage DC voltage control circuit,
The output of the second-stage DC voltage control circuit is used as a lower limit value for the output value of the third-stage DC voltage control circuit,
A control device for an AC / DC converter, wherein the output of the DC voltage control circuit in the third stage is used as a final control output value for the DC voltage and active power. 13. In a control device for an AC / DC converter in a DC transmission system, wherein a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, a set value and an effective power of active power that the converter accommodates. The value obtained by multiplying the difference value of the detected value of electric power by each individual proportional coefficient is added to the DC voltage setting value, the upper limit value for the DC voltage setting value, and the lower limit value for the DC voltage setting value to correct each. , The corrected DC voltage setting value is restricted so as not to deviate from the range between the corrected upper limit value and the corrected lower limit value, and the restricted DC voltage setting value and the DC voltage detection value are controlled to be equal. A control device for an AC / DC converter, characterized by: 14. A control device for an AC / DC converter in a DC power transmission system, wherein a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit. Correction means for correcting the three types of DC voltage set values by adding respective multiplication values obtained by multiplying the difference between the set value of the active power of the converter and the detected value, respectively,
A first-stage DC voltage control circuit for performing control by the correction means so that the value obtained by correcting the DC voltage setting value of the intermediate value among the three types of DC voltage setting values becomes equal to the DC voltage detection value; A second-stage DC voltage control circuit for performing control so that the value obtained by correcting the largest DC voltage setting value among the three types of DC voltage setting values becomes equal to the detected DC voltage value by the means; Control is performed so that the value obtained by correcting the smallest DC voltage setting value among the three types of DC voltage setting values becomes equal to the DC voltage detection value.
A DC voltage control circuit of a second stage, wherein the output of the DC voltage control circuit of the first stage is used as an upper limit value for the output value of the DC voltage control circuit of the second stage,
The output of the second-stage DC voltage control circuit is used as a lower limit value for the output value of the third-stage DC voltage control circuit,
A control device for an AC / DC converter, wherein the output of the DC voltage control circuit in the third stage is used as a final control output value for the DC voltage and active power. 15. A control device for an AC / DC converter in a DC transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, and a setting value and detection of active power that the converter accommodates. A value proportional to the difference between the values and the magnitude of the difference between the set value of the active power and the detected value deviating from the preset range are added, and the added value is further added to the set value of the DC voltage to obtain the DC voltage. A controller for an AC / DC converter, which corrects a set value and controls so that the corrected DC voltage set value and the detected DC voltage are equal. 16. A controller of an AC / DC converter in a DC power transmission system, wherein a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, and a difference between a DC voltage set value and a DC voltage detection value is detected. A proportional value,
The difference between the DC voltage set value and the DC voltage detected value is added to a magnitude deviating from a preset range, and the added value is further added to the active power set value to correct the set value of active power. A control device for an AC / DC converter, wherein the corrected active power set value and the detected active power value are controlled to be equal to each other. 17. A controller of an AC / DC converter in a DC transmission system in which a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, and is proportional to a difference between a detected value and a set value of active power. Value is controlled so that the difference between the intermediate value of the DC voltage setting value and the detected value of the DC voltage among the three different values of the DC voltage setting value deviates from the preset range. A first-stage DC voltage control circuit, and a second-stage DC voltage control circuit that performs control so that the DC voltage setting value of the largest value among the three types of DC voltage settings becomes equal to the DC voltage detection value. A DC voltage control circuit of a third stage for controlling the DC voltage setting value of the smallest value among the three types of DC voltage settings to be equal to the detected value of the DC voltage; The output of the voltage control circuit Use as an upper limit value for the output value of the DC voltage control circuit of the serial second stage,
The output of the second-stage DC voltage control circuit is used as a lower limit value for the output value of the third-stage DC voltage control circuit,
A control device for an AC / DC converter, wherein the output of the DC voltage control circuit in the third stage is used as a final control output value for the DC voltage and active power. 18. In a control device for an AC / DC converter in a DC power transmission system, wherein a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, a set value and detection of active power interchanged by the converter. An AC / DC converter characterized by correcting the DC voltage setting value by adding a value proportional to the power of the difference between the values and controlling so that the corrected DC voltage setting value and the DC voltage detection value become equal. Control device. 19. A control device in an AC / DC converter of a DC power transmission system, wherein a plurality of AC / DC converters for converting AC power and DC power are connected by a DC circuit, wherein the difference between the DC voltage setting value and the DC voltage detection value is An AC / DC converter characterized by correcting a set value of active power accommodating by the converter by adding a value proportional to a power, and controlling the corrected active power set value and the detected active power to be equal. Control device.